Generated by TXTS2HTM.BAT, (c) John Paul Jones, 2000
QBasic Statements:
BLOAD Statement
BEEP Statement
BSAVE Statement
COM Statement
COLOR Statement
CALL Statement
CHAIN Statement
CALL ABSOLUTE Statement
CHDIR Statement
CONST Statement
COMMON Statement
CIRCLE Statement
CLEAR Statement
CLNG Statement
CLOSE Statement
CLS Statement
DIM Statement
DATE$ Statement
DATA Statement
DECLARE Statement
DO WHILE Statement
DO UNTIL Statement
DEF FN Statement
DEF SEG Statement
DRAW Statement
DEFDBL Statement
DEFINT Statement
DEFLNG Statement
DEFSNG Statement
DEFSTR Statement
ENVIRON Statement
END Statement
ERASE Statement
EXIT Statement
ERROR Statement
FOR Statement
FILES Statement
FUNCTION Statement
FIELD Statement
GOTO Statement
GET Statement (File I/O)
GET Statement (Graphics)
GOSUB Statement
INPUT# Statement
INPUT Statement
IF Statement
IOCTL Statement
KILL Statement
KEY Statement
KEY(n) Statements
LINE INPUT Statement
LPRINT USING Statement
LINE Statement
LET Statement
LOCATE Statement
LPRINT Statement
LOCK Statement
LSET Statement
MID$ Statement
MKDIR Statement
NAME Statement
ON ERROR Statement
ON EVENT Statement
OPEN Statement
OUT Statement
OPTION BASE Statement
ON expression Statement
PSET Statement
PRINT Statement
PRINT USING Statement
POKE Statement
PRESET Statement
PCOPY Statement
PAINT Statement
PEN Statement
PUT Statement (File)
PUT Statement (Graphics)
PLAY Statement
PALETTE Statement
PLAY Statements (Event Trapping)
READ Statement
REM Statement
RMDIR Statement
RUN Statement
RESET Statement
RETURN Statement
RSET Statement
RESUME Statement
REDIM Statement
RESTORE Statement
RANDOMIZE Statement
SELECT CASE Statement
SYSTEM Statement
SLEEP Statement
SOUND Statement
STOP Statement
STATIC Statement
SHELL Statement
SEEK Statement
SHARED Statement
SCREEN Statement
SWAP Statement
SUB Statement
STRIG Statement
TYPE Statement
TRON Statement
TIME$ Statement
TIMER Statement
TROFF Statement
UNLOCK Statement
VIEW Statement
VIEW PRINT Statement
WRITE Statement
WIDTH Statement
WHILE WEND Statement
WINDOW Statement
WAIT Statement
QBasic Functions:
ASC Function
ATN Function
ABS Function
CHR$ Function
COMMAND$ Function
CINT Function
CDBL Function
COS Function
CSNG Function
CLNG Function
CVD Function
CSRLIN Function
CVDMBF Function
CVI Function
CVL Function
CVS Function
DATE$ Function
EOF Function
ERR Function
ERL Function
EXP Function
ERDEV Function
ERDEV$ Function
FIX Function
FRE Function
FREEFILE Function
FILEATTR Function
HEX$ Function
INSTR Function
INPUT$ Function
INT Function
INKEY$ Function
INP Function
IOCTL$ Function
LTRIM$ Function
LCASE$ Function
LEFT$ Function
LEN Function
LOF Function
LBOUND Function
LOG Function
LOC Function
LPOS Function
MID$ Function
MKD$ Function
MKDMBF$ Function
MKI$ Function
MKL$ Function
MKS$ Function
MKSMBF$ Function
OCT$ Function
POS Function
PEEK Function
PMAP Function
POINT Function
PEN Function
PLAY Function
RTRIM$ Function
RND Function
RIGHT$ Function
SEEK Function
SGN Function
STRING$ Function
STR$ Function
SPACE$ Function
SPC Function
SQR Function
SIN Function
STICK Function
STRIG Function
SCREEN Function
TAN Function
TAB Function
TIME$ Function
TIMER Function
UBOUND Function
UCASE$ Function
VAL Function
VARSEG Function
VARPTR Function
VARPTR$ Function
BLOAD Statement
BLOAD Statement
---------------
Loads memory image file created by BSAVE statement into
memory at the specified location
Usage: BLOAD filename[,offset]
* offset is the optional offset from the start of the
data segment (or last DEF SEG)), indicating where the image
is to be loaded.
* filename is a string expression that specifies the
file containing the image to load.
* BLOAD and BSAVE work together to provide you with
a quick and convenient way to load array values
or graphics images.
* Do not use BLOAD with files created by BASICA,
QBASIC and BASICA store items differently in
memory.
Example:
'Create an array called sales
DIM sales (1 TO 500)
'Set the segment address to the start of SALES
DEF SEG = VARSEG(sales(1))
'Load the array using BLOAD
BLOAD "SALES.DAT", VARPTR(sales(1))
'Return the the BASIC data segment
DEF SEG
Related functions: VARPTR, VARSEG
Related Statements: BSAVE, DEF SEG
BEEP Statement
BEEP statement
--------------
Sounds the computers built-in speaker.
Usage: BEEP
BSAVE Statement
BSAVE statement
---------------
Copies the contents of a memory region to an output file or device.
Usage: BSAVE filename, offset, length
* filename is a string expression that specifies
the file or device to which memory will be
transfered.
* offset is the location within the current segment
of thefirst byte you want to copy.
* length is the number of bytes to copy (from 0 to
65,535).
* BSAVE performs a byte-by-byte copy. If you save
the memory contents to a file, you can later use
BLOAD to restore the memory image.
Example:
'Create an array with 500 elements
'Initialize the array with values from 1 through 500
DIM sales(1 TO 500)
FOR i = 1 TO 500
sales(i) = i
NET i
'Set the segment address to the start of sales
DEF SEG = VARSEG(sales(1))
'Save the array using BSAVE
BSAVE "SALES.DAT", VARPTR(sales(1)), 2000
'Return the Basic data segment
DEF SEG
Related functions: VARPTR, VARSEG
Related statements: BLOAD, DEF SEG
COM Statement
COM Statement
-------------
Enables or disables data communications eveent
trapping on the specified port.
Usage: COM(n) ON
or
COM(n) OFF
or
COMn) STOP
Notes:
* n is the comunications port number (1 or 2).
* COM ON enables communications event trapping.
If a character arrives at the port, your
program will execute the subroutine defined
by the ON COM statement.
* COM OFF disables communications event
trapping. Characters arriving at the port
are ignored.
* COM STOP prevents event trapping until the
program executes a COM ON statement. Events
are processed once trapping is enabled.
Example:
ON COM(1) GOSUB ComHandler
COM(1) ON
Related statements: ON event GOSUB
COLOR Statement
COLOR Statement
---------------
Sets the screen color.
Usage: COLOR[foreground][,background][,border]]
(screen mode 0)
COLOR[background][,palette]
(screen mode 1)
COLOR [foreground][,background]
(screen modes 7-10)
COLOR [foreground]
(screen modes 4, 12, 13)
Notes:
* The COLOR statement allows you to set text foreground
and background colors as well as color pallette in
graphics mode.
* See the SCREEN statement for specifics on each screen
mode.
* In screen mode 0, you can set the text foreground
color to one of 16 colors (0 through 15). To use
the blinking version of the color, add value 16 to
the color, yeilding a value in the range of 16 to
31. The background screen border must be a color
value from 0 to 15.
* In screen mode 1, you can specify a palette value
in the range 0 through 255. The palette determines
which of two sets of colors to use for graphics
display.
* In screen modes 7 through 10, the foreground
color is an attribute number and the background
color is a color number.
* Int screen modes 4, 12, and 13, the foreground
color is an attribute number. You cannot
specify a background color.
Example:
SCREEN 0
FOR fcolor = 0 TO 31
COLOR fcolor
PRINT "Current color is"; fcolor
INPUT dummy$
NEXT fcolor
Related functions: POINT, SCREEN
Related statements: CIRCLE, DRAW, LINE, PAINT
PALETTE, PALETTE USING, PRESET, PSET, SCREEN
CALL Statement
CALL Statement
--------------
Transfers control to a Basic subprogram.
Usage: CALL subprogram_name[(argument_list)]
or
subprogram_name[argument_list]
* subprogram_name is the name of a Basic subprogram crated using
a SUB statement.
* argument_list is a list of parameters seperated by comas. The
subprogram can change the values of the parameters.
* You can call subprograms with or without the CALL keyword If
you omit CALL, do not pace the arguments within parentheses.
Also, if ou omit CALL, you must use the DECLARE statement. If
you omit a declaration, QBasic willsupply it automatically.
* To prevent a subprogram from changing a parameter's value,
simply put the parameter in parentheses: CALL TEST (a, b, (c))
* In this case, the subprogram can change the values of the
parameters 'a' and 'b' but not 'c'.
Example:
DECLARE SUB SwapVal (a, b)
a = 1
b = 2
Call SwapVal(a, b)
PRINT a; b
END
SUB SwapVal(x, y)
temp = x
x = y
y = temp
END SUB
Output of this program:
2 1
Related statements: CALL ABSOLUTE, CHAIN, DECLARE
CHAIN Statement
CHAIN Statement
---------------
Transfers control from one QBASIC program to another.
Usage: CHAIN filename
Notes:
* filename is a character string containing the filename of
the program to which control is to be passes.
* To exchange information between chained programs, you
must use the COMMON statement.
* After you transfer control to another program using
CHAIN, the program that called CHAIN does not resume
control when the chained program completes.
Example:
CHAIN "TEST.BAS"
Related statements: CALL, COMMON, RUN
CALLABSO Statement
CALL ABSOLUTE Statement
-----------------------
Transfers control to a machine language subroutine.
Usage: CALL ABSOLUTE ([parameter_list,]offset)
Notes:
* parameter_list is an optional list of parameters seperated
by comas.
* offset is the location within the current code segment of
the start procedure.
Example:
'Create a machine-language procedure and
'call it using CALL ABSOLUTE
'Array to store machine code
DIM Asmroutine(1 TO 6) AS INTEGER
'Data that makes up machine-code routine
DATA &H55 : 'PUSH BP
DATA &H8B, &HEC : 'MOV BP, SP
DATA &HB4, 2 : 'MOV AH, 2
DATA &HB2, 65 : 'MOV DL, 65
DATA &HCD, &H21 : 'INT 21H
DATA &H5D : 'POP BP
DATA &HCB, 0 : 'RET
'Get array offset
offset = VARPTR(asmroutine(1))
'Change the segment to the start of the array
DEF SEG = VARSEG(asmroutine(1))
'Fill the array with machine code
FOR i = 0 TO 11
READ asmcode
POKE (offset + i), asmcode
NEXT i
'Call the routine and restore the segment
CALL ABSOLUTE(VARPTR(asmroutine(1))
DEF SEG
Related Statements: CALL
CHDIR Statement
CHDIR Statement
----------------
Changes the default directory for the specified drive.
Usage: CHDIR directory_name
Notes:
* directory_name is a string expression containing the
desired directory name. It must have fewer than 64
characters
* To change the default directory for a drive other than the
current drive, precede the pathname with a disk drive
letter and colon.
* CHDIR does not change the default drive.
Example:
'Change the current directory in drive C to \DOS
CHDIR "C:\DOS"
Related statements: FILES, MKDIR, RMDIR
CONST Statement
CONST Statement
---------------
Defines a symbolic constant.
Usage: CONST symbol_name = expression[,symbol_name = expression]...
Notes:
* constants allow programs to use symbolic
names in place of numeric or string values.
* symbol_name is the name the constant will
have throughout the program. You cannot
change the value of a constant once you've
defined it.
* expression is a numeric or string expression
assigned to the constant. You cannot use
variables or functions in the expression.
* Constants defined in a subprogram or
function are local to that subprogram or
function.
Example:
CONST true = 1
CONST daysperweek = 7
'Use of constant in array declaration
DIM Days(daysperweek)
COMMON Statement
COMMON Statement
----------------
Defines variables as global within a module
or between chained programs.
Usage: COMMON [SHARED]variable_list
CIRCLE Statement
CIRCLE Statement
----------------
Drawa a circle or ellipse with the specified
radius and center.
Usage: CIRCLE[STEP](x,y),radius[,[color][,[start_angle]
[,[end_angle][,aspect_ratio]]]]
Notes:
* STEP is an optional keyword that tells CIRCLE that
the x and y values are offsets from the current
graphics cursor
* x,y are the coordinates of the circle's center
* radius is the radius of the circle in the current
coordinate system.
* color is the border color for the circle. The circle
is not filled.
* start_angle is the starting angle in radians for the
arc. The default is 0.
* end_angle is the ending angle in radians for the arc.
The default is 2 pi.
* aspect_ratio is the ratio of the length of the y axis
to the length of the x axis. By changing the aspect
ratio, you can create ellipses.
Example:
'Fill the screen with random circles
SCREEN 1
FOR i = 1 TO 100
x = INT(320 * RND)
y = INT(200 * RND)
RADIUS = INT(100 * RND)
CIRCLE (x,y), RADIUS
NEXT i
SCREEN 0
Related functions: POINT
Related statements: COLOR, DRAW, LINE, PAINT,
PRESET, PSET, SCREEN
CLEAR Statement
CLEAR Statement
---------------
Initializes all program variables, closes all files,
and optionally defines the stack size.
Usage: CLEAR [,,stack_size]
Notes:
* CLEAR loses all open files, sets numeric variables
and arrays to 0, and sets all string variables to
zero length.
* If your program uses recursion or performs several
levels of subroutine calls, you might need to increase
your program's stack size
* stack_size is the size of the stack in bytes. You
must precede the stack size with two commas shown.
* The default stack size is 2048 bytes
* Do not execute CLEAR within a subroutine
Example:
'Initialize variables and create a stack of 4096 bytes
CLEAR , , 4096
Related functions: FRE
Related statements: ERASE
CLNG Statement
CLNG Statement
--------------
Rounds a numeric expression to a long (4-byte) integer.
Usage: CLNG(numeric_expression)
Notes:
* numeric_expression must evaluate to a value in the
range -2,147,483,648 through 2,147,483,647. If
the result is outside this range, a runtime error
occurs.
Example:
PRINT CLNG(338457.8)
PRINT CLNG(2147358.28)
Output:
338458
2147358
Related functions: CDBL, CINT, CSNG
CLOSE Statement
CLOSE Statement
---------------
Close one or more files or devices opened by the OPEN
statement.
Usage: CLOSE[[#]file_number[,[#]file_number]...
Notes:
* file_number is the file number assigned to the file
or device in its OPEN statement.
* You can specify more than one file number in a single
CLOSE statement.
* Once you close a file number, you cannot use the file
number for read or write operations until you open a
new file.
* The CLEAR, END, RESET, RUN, and SYSTEM statements
close your files automatically.
* CLOSE with no arguments closes all OPEN files and
deviices.
Example:
OPEN "TEST.DAT" FOR OUTPUT AS #1
PRINT "This is a test."
CLOSE #1
Related statements: OPEN, RESET
CLS Statement
CLS Statement
-------------
Clears the screen display.
Usage: CLS[{0|1|2}]
Notes:
* Depending on the region of the screen that
you want to clear, CLS gives you four
options:
Statement Result
CLS Clears text or graphics viewport
CLS 0 Clears entire screen of text and graphics
CLS 1 Clears only the graphics viewport
CLS 2 Clears only the text viewport, leaving
the bottom line unchanged.
Example:
CLS
Related statements: VIEW, VIEW PRINT, WINDOW
DIM Statement
DIM Statement
-------------
Declares an array variable and allocates storage.
Usage:
DIM[SHARED]variable_name[(subscripts)][AS type][,variable_name[(subscripts)][AS type]...
Notes:
* The SHARED keyword allows subprograms and functions
to share the same variable without passing the variable as
a parameter.
* variable_name is the name of the array.
* subscripts is the dimensions of the array. If you have not
previously defined an array in a DIM statement, you can
assign a value to an element that has subscript ranging
from 0 to 10. You can change the lower and upper bounds
as shown here:
DIM a(0 TO 8) 'a(0) to a(8)
DIM b(1 TO 10) 'b(1) to b(10)
* If you specify only one subscript, QBasic assumes that it
is the upper bound and uses 0 for the lower bound unless
you include an OPTION BASE statement.
* For multidimensional arrays, simply seperate the subscripts
of each array dimension with commas:
DIM (box(3,3)
DIM (bigbox(1 TO 10, 1 TO 10)
* The maximum number of array dimensions is 60.
* Valid types include INTEGER, LONG, SINGLE, DOUBLE, STRING,
and user defined types.
Example:
DIM a(25 TO 100) AS INTEGER
DIM b(1 TO 10, 1 TO 5) AS DOUBLE
TYPE Schedule
day AS STRING * 10
hours AS INTEGER
END TYPE
DIM workday AS Schedule
Related functions: LBOUND, UBOUND
Related statements: ERASE. OPTION BASE, REDIM
DATE$ Statement
DATE$ Statement
---------------
Sets the system date.
Usage: DATE$ = string_expression
Notes:
* string_expression is a string expression
containing the desired date in the form
"mm-dd-yyyy", where yyyy is the year 1980
through 2099.
* If you specify only the last two digits of
the year, DATE$ assumes that the first two
digits are 19.
Example:
DATE$ = "12-25-89"
DATA Statement
DATA Statement
--------------
Stores numeric and string constants
to be read by the READ statement.
Usage: DATA constant[,constant]...
Notes:
* READ statements access DATA statements in
the order the data segments appear in the
program. The RESTORE statement allows
your program to reread DATA statements as
necessary.
* The type of variable in a READ statement
must match the type of the constant in the
DATA statement.
* You can only use one data statement at the
module level, never in a procedure.
Example:
DATA 1, .2345, "TEST", 98765
READ a%, b#, c$, d$
PRINT a%, b#, c$, d$
Output:
1 2,2345 TEST 98765
Related statements: READ, RESTORE
DECLARE Statement
DECLARE Statement
-----------------
Declares a procedure and directs QBasic to perform
type checking for each paramenter.
Usage: DECLARE {FUNCTION|SUB} procedure_name [(argument_list])]
Notes:
* DECLARE directs QBasic to ensure that the types of
parameters passed to a procedure match the types
that the procedure expects.
* DECLARE is needed only when you don't use the
CALL statement.
* The keyword FUNCTION indicates that the procedure
is a function; likewise, SUB indicates a subprogram.
* procedure_name is the name of the function or
subprogram.
* argument_list is an optional list of parameters
seperated by commas. For compiler type checking,
specify argument as follows:
variavle_name [AS type]
* Valid types include INTEGER, LONG, SINGLE, DOUBLE,
STRING, ANY or a user-defined type.
Example:
See CALL
Related statements: CALL, FUNCTION, SUB
DOWHILE Statement
DO WHILE Statement
------------------
Repeats a set of nstructions while a condition is true.
Usage: DO WHILE Boolean_expression
statements
LOOP
or
DO
statements
LOOP WHILE Boolean_expression
Notes:
* Boolean_expression is an expression that evaluates
to true or false.
* The first form of the statement first tests the
Boolean expression. If the expression is true,
QBasic executes the statements within the loop
until the expression becomes false.
* The second form of the statement fist executes the
statements within the loop and then tests the
boolean expression. If the expression is true,
QBasic repeats the statements; otherwise, execution
continues at the first statement after the loop.
Example:
i = 0
DO WHILE i < 100
PRINT i
i = i + 1
LOOP
Related statements: DO UNTIL, EXIT, FOR, WHILE/WEND
DOUNTIL Statement
DO UNTIL Statement
------------------
Repeats a set of instrictions until a condition
becomes true.
Usage: DO UNTIL Boolean_expression
statements
LOOP
or
DO
statements
LOOP UNTIL Boolean_expression
Notes:
* Boolean_expression is an expression that
evaluates to true or false.
* The forst form of the syatement first tests the
Boolean expression. If the expression is true,
QBasic skips the statements within the loop and
continues execution at the first statement that
follows the loop.
* The second form of the statement first performs
the statements within the loop and then tests
the Boolean expression. If the Boolean express-
sion is false, QBasic repeats the statements in
the loop; if the expression is true, QBasic
continues execution at the forst statement that
follows the loop.
Example:
i = 0
DO
PRINT i
i = i + 1
LOOP UNTIL 1 = 100
Related statements: DO WHILE, EXIT, FOR, WHILE/WEND
DEFFN Statement
DEF FN Statement
----------------
Defines a function.
Usage: DEF FNname [(argument_list)] = expression
or
DEF FNname [argument_list)]
.
.
.
FNname = expression
.
.
.
END DEF
Notes:
* Function names must begin with FN and can contain
up to 40 characters. The function name indicates
the value type the function returns:
Function name Returns
FNday$ string
FNcount% integer
FNaverage# single precision value
* For a function to return a value, the function must
assign its result to the function name.
* argument_list is a list of parameters to the function
seperated by commas as follows:
arument_name [AS type]
* You cannot use a function before your program defines
it, nor can you use DEF FN functions recursively.
Example:
DEFSEG Statement
DEF SEG Statement
-----------------
Sets the current segment address for susequent
PEEK functions and BLOAD, BSAVE, CALL ABSOLUTE,
and POKE statements.
Usage: DEF SEG [= address]
Notes:
* address is an integer expression in the range
0 through 65,535. If you omit address, QBasic
uses the Basic data segment.
Example:
See CALL ABSOLUTE statement
Related functions: PEEK
Related statements: BLOAD, BSAVE, CALL ABSOLUTE,
POKE
DRAW Statement
DRAW Statement
--------------
Draws an object specified in a string
expression.
Usage: DRAW string_expression
Notes:
* DRAW uses a string containing graphics
commands to draw an object. The
string can contain cursor, color, and
scaling commands.
* Cursor movement commands are as follows:
Command Description Command Description
U(n) Up n untis G(n) Down & left n units
D(n) Down n units H(n) Up & left n units
L(n) Left n units M[{-|+}]xy moves to x,y (If
R(n) Right n units you precede x,y
E(n) Up & right n with a minus or
units plus sign, movement
F(n) Down & right is relative to the
n units current position of
the cursor.)
If you omit n, the cursor moves 1 unit.
* DRAW allows you to precede the cursor movement
functions with B and N:
Command Description
B Move but do not draw points
N Move but return to original position once
drawn
* Angle, color, and scaling commands are as follows:
Command Description
A rotation Set rotation angle in the degrees:
0=0 degrees, 1 = 90 degrees, 2 = 180
degrees, 3 = 270 degrees
TA degree Turn angle (-360 degrees through 360
degrees)
C color Set color
S n Set scale factor for units (The default
is 4, 1 pixel)
P color, Paint the interior of the object color;
border the color of the border must be border.
Example:
'Draw a box & fill it in
SCREEN 1
DRAW "C3"
DRAW "L20U20R20D20" ' draw box
DRAW "BH10" ' move into box
DRAW "P2,3" ' paint box
Related funtions: POINT
Related statements: CIRCLE, COLOR, LINE, PAINT, PSET,
PRESET, SCREEN
DEFDBL Statement
DEFDBL Statement
----------------
Defines the default data type as double-precision
for variables whose names begin with a letter in
the specified range.
Usage:
DEFDBL letter[-last_letter][,letter[-last_letter]...
Notes:
* letter and last_letter are a range of letters
to associate with a type. QBasic does not
distinguish between uppercase and lowercase
variables.
* If a variable name has the suffix %, &, !, or
$, the data type associated with the suffix
takes precedence over the default type
statement.
Example:
DEFDBL A-J
Related statements: DEFINT, DEFLNG, DEFSNG,
DEFSTR
DEFINT Statement
DEFINT Statement
----------------
Defines the default data type as an integer
for a variable whose names begin with a
letter.
Usage: DEFINT letter[-last_letter][,letter[-last_letter]]...
Notes:
* See DEFDBL
Example DEFINT X-Z
Related statements: DEFDBL, DEFLNG, DEFSNG, DEFSTR
DEFLNG Statement
DEFLNG Statement
----------------
Defines the default data type as long for variables
whose names begin with a letter in a specified
range.
Usage: DEFLNG letter[-last_letter][,letter[-last_letter]]...
Notes:
* See DEFDBL
Example: DEFINT X-Z
Related statements: DEFDBL, DEFLNG, DEFSNG, DEFSTR
DEFSNG Statement
DEFSNG Statement
----------------
Defines the default data type as single-precision
for variables whose names begin with a letter in
the specified range.
Usage: DEFSNG letter[-last_letter][,letter[-last_letter]]...
Notes:
* See DEFDBL
Example:
DEFSNG T-W
Related statements: DEFDBL, DEFINT, DEFLNG, DEFSTR
DEFSTR Statement
DEFSTR Statement
----------------
Defines the default data type as string for
variables whose names begin with a letter in
the specified range.
Usage: DEFSTR letter[-last_letter][,letter[-last_letter]]...
Notes:
* See DEFDBL
Example:
DEFSNG T-W
Related statements: DEFDBL, DEFINT, DEFLNG, DEFSNG
ENVIRON Statement
ENVIRON Statement
-----------------
Cahnges an existing entry or places a new entry in
the MS-DOS environment.
Usage: ENVIRON string_expression
Notes:
* The ENVIRON statement expects a string expression
of the same form as the MS-DOS SET command.
* The chsnges to the environment table is valid only
for the life of the program.
* You cannot increase the size of the MS-DOS environment
in QBasic. To make space in the DOS environment for
use by QBasic programs, create a dummy entry with the
DOS SET command Then erase the contents of the entry
in a QBasic program to make room for new or changed
variables.
Example:
ENVIRON "PROGRAM=TEST"
PRINT ENVIRON$("PROGRAM")
Output:
TEST
Related functions: ENVIRON$
* The environment variable entry will last only as the
QBasic program is running, not when you exit from the
program to DOS.
END Statement
END Statement
-------------
Ends a Qasic program.
Usage: END
* END by itself ends program and closes all files.
* The END statement is also used with DEF FN, fUNCTION,
IF, SELECT CASE, SUB, TYPE. Tose forms of END are
discussed in relation to the ppropriate statements.
Example:
FOR i = 1 TO 10
PRINT i
NEXT i
END
Related statements: DEF FN, FUNCTION, IF, SELECT CASE,
SUB, TYPE
ERASE Statement
ERASE Statement
---------------
Reinitializes the elements of a static array
or deallocates dynamic arrays.
Usage: ERASE array[,array]...
Notes:
* array is the number of the array to reinitialize
or deallocate.
* For static numeric arrays, ERASE sets each element
to zero. For static string arrays, ERASE sets
each element to null.
* For dynamic arrays, ERASE frees the memory used
by the specified arrays.
Example:
DIM a(100)
FOR i = 1 TO 100
a(i) = i
NEXT i
ERASE a ' Reinitialize A
FOR i = 1 TO 100
PRINT a(i)
NEXT i
Related functions: FRE
Related statements: CLEAR, DIM, REDIM
EXIT Statement
EXIT Statements
---------------
Exit a DO or FOR loop, function, or subprogram.
Usage: EXIT DEF
or
EXIT DO
or
EXIT FOR
or
EXIT FUNCTION
or
EXIT SUB
Notes:
* FOR DO and FOR loops, execution continues
at the first statement following the loop.
* For functions and subprograms, execution
continues at the statement following the
statement that called the function or sub-
routine.
Example:
J = 30
FOR i = 1 TO 50
IF i = j THEN
EXIT FOR
END IF
NEXT i
PRINT "Ending value is"; i
Output:
Ending value is 30
Related statements: DEF FN, DO UNTIL, DO WHILE,
FOR, FUNCTION, SUB
ERROR Statement
ERROR Statement
---------------
Simulates an occurance of the error number
specified. Allows a program to define its
error codes.
Usage: ERROR numeric_expression
Notes:
* numeric expression is an integer value in
the range 1 to 255.
* See the ERR function for a list of pre-
defined error status codes. To define your
own error code, use an undefined error
value.
* The ERROR statement assigns the error value
specified to ERR and passes control to the
error handler.
Example:
ON ERROR GOTO HANDLER
'Test error handler with error 222
ERROR 222
EndTest:
END
Handler:
PRINT "In error handler with error; ERR
RESUME EndTest
Related functions: ERDEV, ERDEV$, ERL, ERR
Related statements: ON ERROR GOTO, RESUME
FOR Statement
FOR Statement
-------------
Repeats a given set of instructions a specific
number of times.
Usage: FOR control_variable=start_value TO end_value [STEP increment]
.
.
NEXT [control_variable[,control_variable]...]
Notes:
* control_variable is the variable that FOR increments
with each iteration of the loop. It controls whether
or not QBasic continues the loop.
* start_value is the initial value that QBasic assigns
to the control variable.
* increment is the amount that QBasic adds to the
control variable with each iteration of the loop.
The increment can be a positive or negative value.
* The NEXT statement directs QBasic to increment te
control variable and test whether it is greater than
the end value. If you omit increment, the default
increment is 1.
Example:
FOR i = 1 TO 10
PRINT "i="; i
NEXT i
FOR i = 1 TO 10
FOR j = 1 TO 10
PRINT i; "*"; j; "="; i * j
NEXT j
NEXT i
Related statements: DO UNTIL, DO WHILE, EXIT, WHILE/WEND
FILES Statement
FILES Statement
---------------
Displays the names of files in the current
or specified directory.
Usage: FILES[string_expression]
Notes:
* string_expression is a string expression
that contains an MS_DOS file specification
of the files to isplay.
* If you omit a file specification, FILES
displays the files in the current
directory.
Example:
FILES
FILES ".BAS"
FILES "A:"
Related statements: CHDIR, KILL, NAME
FUNCTION Statement
FUNCTION Statement
------------------
Declares a user-defined function.
Usage:
FUNCTION function_name[(arguments)][STATIC]
Notes:
* function_name is the name of the user-
defined function. The name can end with
a type-declaration character (%, &, !,
#, or $) to indicate the type of value
it returns.
* arguments is an optional list of parame-
ters, seperated by commas, to be passed
to the function.
* The STATIC keyword directs QBasic to save
the values of the function's local
variables between function calls.
* For a function to return a value, the
fuction must at some point assign an
expression to the function name.
Example:
FUNCTION Min% (a AS INTEGER, b AS INTEGER)
IF (a < b) THEN
Min% = a
ELSE
Min% = b
END IF
END FUNCTION
PRINT "Min of 5 and 3 is; Min%(5, 3)
Related statements: DECLARE, DEF FN, SUB, STATIC
FIELD Statement
FIELD Statement
---------------
Allocates space for variables in a random-access
file buffer.
Usage: FIELD [#]file_number, width AS str_variable...
Notes:
* width is the number of characters in the field.
* str_variable is the name of a string variable to
be used when reading from or writing to the file.
* A variable name that appears in a FIELD statement
should not appear in an INPUT statement on the
left side of an assignment operator. If it does,
the variable will no longer reference the random-
access file buffer.
* Using record variables is usually more convenient
than using the FIELD statement.
Example:
OPEN "RANDOM.DAT" FOR RANDOM AS #1 LEN=80
FIELD #1, 76 AS name$, 4 AS salary$
Related statements: GET, LSET, OPEN, PUT, RSET
GOTO Statement
GOTO Statement
--------------
Branches to the specified line number or label.
syntax: GOTO location
Notes:
* location is the line number or label at which execution is
to continue.
* Early vrsions of Basic did not have DO loops, ELSE clauses
or IF statements, or SELECT CASE statements. So GOTO was
used to implement these constructs. To improve your
your program's reliability and simplify debugging, restrict
the use of GOTO.
Example:
i = 0
Start:
PRINT "i ="; i
INPUT "Again"; reply$
IF reply$="N" THEN
END
ELSE
i = i + 1
END IF
GOTO Start
Related statements: DO UNTIL, DO WHILE, SELECT CASE
GET Statement
GET Statement
-------------
Reads a record from a random-access file or
binary disk file.
Usage: GET [#]file_number[,[record_number][,variable]]
GET-G Statement
GET Statement (Graphics)
-------------
Stores a graphics screen image in an array.
Usage:
GET [STEP](xleft,ytop)-[STEP](xright, ybottom), array[(index)]
Notes:
* The keyword STEP indicates that the coordinates
are offsets relative to the last point plotted.
* array is the name of the array in which GET
should store the image.
* index is the array index at which storage of
the graphics image begins.
* GET stores the screen image in the specified
rectangle.
* To calculate the number of bytes required, use
the formula:
4 + INT(((xright - xleft + 1) * (bits_perpiixel/planes)
+ 7)/8) * planes * (ybottom - ytop + 1)
* The number of bits per pixel and the number of
planes depends on the current screen.
Example:
GET (10,20)-20,50), dog
Related statements: PUT (Graphics), SCREEN
GOSUB Statement
GOSUB Statement
---------------
Directs execution to continue at a Basic
subroutine.
Usage: GOSUB location
Notes:
* location is either a line number or label
at which execution should continue.
* Use a RETURN statement to end a subroutine.
* GOSUB is the older method of executing
subroutines. QBasic typically uses SUB and
ALL instead.
* The label is an identifier with a colon
at the end, e.g., Handler:
Related statements: IN event GOSUB,
ON expression RETURN, SUB
INPUT# Statement
INPUT # Statement
-----------------
Usage: INPUT #file_number, variables
Notes:
* file_number is the number assigned to the file in its
OPEN statement
* variables is the list of variables in which to store
data from the file
Example:
OPEN "SALARY.DAT" FOR INPUT AS #1
DO WHILE NOT EOF(1)
INPUT #1, ename$, salary
PRINT ename$, salary
LOOP
CLOSE #1
Related functions: INPUT$
Related statements: INPUT #; LINE INPUT
INPUT Statement
INPUT Statement
---------------
Gets keyboard input.
Usage: INPUT[;]["prompt"{;|,}]variables
Notes:
* A semicolon immediately after INPUT directs
QBasic to leave the cursor on the same line
after the user presses Enter.
* prompt is the optional prompt INPUT displays
on the screen.
* A semicolon after the prompt directs INPUT to
display a question mark after the prompt.
* A comma after the prompt directs INPUT to
suppress the question mark.
* variables is the list of variables to input.
Seperate multiple variables with commas.
* If you enter a type other than the expected
variable type, or enter too many or too few
values, INPUT displays the message 'Redo from
start', and you must reenter the data.
* The user must seperate multiple entries with
commas.
Example:
'Question mark.
INPUT "Enter your name and age"; uname$, age
PRINT uname$, age
'No question mark
INPUT "Enter your name and age", uname$, age
PRINT uname$, age
Related functions: INPUT$
Related statements: INPUT #; LINE INPUT
IF Statement
IF Statement
------------
Provides conditional execution on the evaluation
of an expression.
Usage; IF expression THEN true_statement[ELSE false_statement]
or
IF expression THEN
[true_statements]
ELSEIF expression THEN
[true_ststatements]]
.
.
[ELSE
[false_statements]]
END IF
Notes:
* The first form of the statement allows you to execute a
single statement if the expression is true and a
different statement if the expression is false.
* The second form of the statement allows you to execute
a series of statements if the expression is true and
a different set if the expression is false. Also,
this syntax allows you to test for a series of different
conditions, one after another.
Example:
F (a > b) THEn max = a SLSE max = b
IF (a > max) THEN CALL BigValue(a)
IF (day$ = "MONDAY") THEN
CALL Meetings
CALL Dinners
ELSE
CALL Gym
END IF
IF (DAY$ = "MONDAY" THEN
CALL Meetings
ELSEIF (DAY$ = "ThURSDAY") THEN
CALL Tickets
ELSEIF (DAY$ = "FRIDAY") THEN
CALL Theatre
END IF
Related statements: ON expression, SELECT CASE
IOCTL Statement
IOCTL Statement
---------------
Transmits a device control string to a
device driver.
Use: IOCTL [#]file_number, control_string
Notes:
* file_number is the file number assigned
to the device in its OPEN statement.
* control_string is a string expression that
specifies the command sent to the device.
* For inormation on device control string
commands, refer to your hardware manual.
Related functions: IOCTL$
KILL Statement
KILL Statement
--------------
Deletes a file from disk.
Usage: KILL file_specification
* file_specification is a string expression
specifying the line to delete. The string
can contain the MS-DOS wildcard characters
? and *.
Example:
KILL "TEST.DAT"
KILL "*.TMP"
Related statements: FILES
KEY Statement
KEY Statement
-------------
Assign string values to the function keys F1
through F12. Optionally, display values of
each key.
Usage: KEY function_key, string_expression
or
KEY LIST
or
KEY ON
or
KEY OFF
Notes:
* function_key is the number of the desired
function key. 1 cooresonds to F1; 10
cooresponds to F10. Use 30 and 31 to rep-
resent keys F1 and F12.
* string_expression is a string of up to 15
characters that you want to assign to the
function key.
* Once you assign a string to a key, QBasic
substitutes the string each time the user
presses the cooresponding function key.
* KEY LIST displays the entire 15-character
assignment for each key.
* KEY ON displays accross the bottom of the
screen the first six letters of the
stings assigned to keys F1 through F10.
* KEY OFF erases the display of the key
assignments from the screen.
Example:
'Assign a stin to F1
KEY 1, "F1 function key"
'Display the key assignment
KEY ON
INPUT "Press the F1 key"; x$
PRINT x$
KEYN Statement
KEY(n) Statements
-----------------
Enable or diable software trapping of
specific keys.
Use: KEY(n) ON
or
KEY(n) OFF
or
KEY(n) STOP
Notes:
* n is the number associated with a
function key, a direction key, or
a user-defined key:
Value of n Meaning
1 to 10 Function keys F1 to F10
11 Up arrow key
12 Left arrow key
13 Right arrow key
14 Down arrow key
15 to 25 User-defined keys
30 and 31 F11 and F12 keys
* KEY(n) ON enables keyboard event trapping
for specified key, KEY(n) OFF disables
keyboard event trapping for specified key.
QBasic does not queue events that occur.
* KEY(n) STOP inhibits event trapping for
the specified key--events are processed
once trapping is enabled.
LINEINPU Statement
LINE INPUT Statement
--------------------
Reads a string of up to 255 characters
Usage: LINE INPUT [;]["prompt";]string_variable
or
LINE INPUT [#]file_number, string_variable
Notes:
* Although the INPUT statement interprets a comma as a
seperator between two entries, the LINE INPUT statement
does not. The LINE INPUT statement reads all characters
up to the carriage return and assigns them to a string
variable.
* If present, the semicolon immediately following the key-
word INPUT directs LINE INPUT to leave the cursor on
the same line after the user presses Enter.
* prompt is an optional message that directs the user to
enter data
* string_variable is the string variable to which LINE
INPUT assigns the information entered
* file_number is the file number assigned to the file in its
OPEN statement
Example:
LINE INPUT "Enter last name, first name, MI: "; fullname$
PRINT fullname$
Related functions: INPUT$
Related statements: INPUT, INPUT #
LPRINTUS Statement
LPRINT USING Statement
----------------------
Prints formatted output on the printer LPT1.
Usage: LPRINT USING format_string; output_list[{|,}]
Notes:
* format_string is the output format. See PRINT
USING for a list of ofrmatting characters.
* output_list is a list of numeric and string
expressions to be printed. Expressions must
be seperaed by commas or semicolons.
* A semicolon following the output list leaves
the print head at the next character position.
A comma leaves the print head at the next
print zone. Print zones are 14 characters
in length. Omitting a semicolon or comma
causes the printer to advance to the beginning
of the next line.
Example:
See PRINT USING
Related statements: LPRING, PRINT USING, WIDTH
LINE Statement
LINE Statement
--------------
Draws a lone or box on the screen.
Usage:
LINE [STEP](x1,y1)]-[STEP](x2,y2)[,[color][,[B[F]][,linestyle]]]
Notes:
* LINE draws either a line using the coordinate
pairs (x1,y1) and (x2,y2) as endpoints or a box
with (x1,y1) as one corner and [x2,y2) as the
opposite corner.
* The keyword STEP directs LINE to use the coord-
inates as an offset from the last point plotted
as opposed to physical coordinates.
* color is the line or box color
* B directs LINE to draw a box rather than a line
* F directs LINE to fill the box with the
specified color.
* linestyle is a 16-bit value whose bits determine
whether or not pixels are drawn. By changing
this value, you change the style of ines on your
screen.
Example:
'Fill the screen with random boxes
SCREEN 1
FOR i = 1 TO 1000
x1 = RND * 320
y1 = RND * 200
x2 = RND * 320
y2 = RND * 200
scolor = RND * 4
LINE(x1,y1)-(x2,y2),scolor, BF
NEXT i
Related functions: POINT
Related statements: CIRCLE, COLOR, DRAW, PAINT, PSET,
PRESET, SCREEN
LET Statement
LET Statement
-------------
Assigns a value to a variable.
Usage: [LET] variable = expression
Notes:
* LET is an optonal keyword used in assignment
statements.
Example:
LET a = 5
'equivalent assignment without LET
a = 5
LOCATE Statement
LOCATE Statement
----------------
Moves the cursor to the specified position on
the screen and, optionally, sets the cursor
size.
Sytax:
LOCATE[row][,[column][,[visible][,[scan_start][,scan_stop]]]]
Notes:
* row is the number of the desired row
* column is the number of the desired column
* visible, when 1, causes the cursor to be displayed.
When 0, it causes the cursor to be hidden.
* scan_start is an integer specifying the first cursor
scan line.
* scan_stop is an integer specifying the last cursor
scan line.
* By changing the cursor scan lines, you can change
the cursor size.
Example:
CLS
FOR i = 5 TO 20
LOCATE, i, i
PRINT Location is"; i; i
NEXT i
Related functions: CSRLIN, POS
LPRINT Statement
LPRINT Statement
----------------
Prints on the printer LPT1.
Usage: LPRINT[output_list][{;|,}]
Notes:
* output_list is a list of numeric and string
expressions to be printed. Expressions must
be seperated by commas or semicolons. See
PRINT USING to see a list of formatting
characters.
* A semicolon following the output list leaaves
the print head at the next character position.
A comma leaves the print head at the next
print zone, where a print zone is 14 characters
in length. Omitting a semicolon or comma
causes the print head to advance to the next
line's beginning.
Example:
LPRINT "This is on line 1"
LPRINT "This is on";
LPRINT " line 2"
Output:
This is on line 1
This is on line 2
Related statements: LPRINT USING, WIDTH
LOCK Statement
LOCK Statement
--------------
Prevents access to all or specific portions
of a file by network programs.
Usage: LOCK([#]file_number[,{record|[start] TO end}]
Notes:
* For random-access files, LOCK locks the specified
record or range of records. For binary files,
LOCK locks specified byte or range of bytes. For
sequential files, LOCK locks the entire file.
* To use LOCK, you should first run SHARE.EXE--an
MS-DOS program that supports file sharing and
locking.
Example:
INPUT "enter record number to update"; rec
LOCK #1, rec ' restricted access
emp.name$ = "SMITH"
PUT #1, rec
UNLOCK rec 'allow access
LSET Statement
LSET Statement
--------------
Moves data into a random-access file buffer,
assigns a variabble of one record type to a
variable of a different record type, or left
justifies the value of a string variable.
Usage: LSET string_variable = string_expression
or
LSET record_variable1 = record_variable2
Notes:
* string_variable is either a random access file
field or a string variable.
* string_expression is any string expression.
* record_variable1 and record_variable2 are
user-defined record variables.
Example:
salary = 77000
LSET e$ = MKS$(salary)
PUT #1
Related statments: RSET
MID$ Statement
MID$ Statement
--------------
Replaces a portion of a string with another
string.
Usage:
MID$(string_variable, start_offset[,num_char]) = string_expression
MKDIR Statement
MKDIR Statement
---------------
Creates a specified MS-DOS directory.
Usage: MKDIR directory_name
Example:
ON ERROR GOTO CheckExists
MKDIR "TSTDIR"
PRINT "Directory TSTDIR created."
Done:
CheckExists:
IF ERR = 75 THEN
PRINT "Directory TSTDIR already exists."
RESUME Done
END IF
ON ERROR GOTO 0
Related statements: CHDIR, RMDIR
NAME Statement
NAME Statement
--------------
Renames a file or directory on disk.
Usage: NAME oldfile_name, AS newfile_name
ONERROR Statement
ON ERROR GOTO Statement
-----------------------
Enables error handling and specifies the first
line of the error handler.
Usage: ON ERROR GOTO location
Notes:
* See ERR for a list of possible errors.
* location is the line number or label of the
handler. A line number of 0 disables error
handling.
* IF error handling is diabled, an error
results in an eror meassage and program
termination.
Example:
ON ERROR GOTO Handler
OPEN "NOFILE.DAT" FOR INPUT AS #1
PRINT "File opened."
CLOSE #1
Done:
END
Handler:
IF ERR = 53 THEN
PRINT "File not found."
END IF
RESUME Done
Related functions: ERDEV, ERDEV$, ERL, ERR
Related statements: ERROR, RESUME
ONEVENT Statement
ON event GOSUB Statements
-------------------------
Specify the first line of an event trapping subroutine
Usage: ON COM(n) GOSUB location
or
ON KEY(n) GOSUB location
or
ON PEN GOSUB location
or
ON PLAY(aueuesize) GOSUB location
or
ON STRIG(n) GOSUB location
or
ON TIMER n) GOSUB location
Notes:
* The ON COM(n) GOSUB statement branches to the
subroutine whenever characters are recieved
at the specified serial port.
* The ON KEY(n) GOSUB statement branches to the
subroutine whenever the key assocoated with
the specified number is pressed.
* These statements do not enable event trapping
but only associate a subroutine with an event.
* The ON TIMER(n) GOSUB statement branches to
the subroutine whenever specified number of
seconds have elapsed. The number of seconds
must be in the range 1 through 86,400.
Example:
ON KEY(10) GOSUB DisplayHelp
KEY(10) ON
PRINT "Press F10 for help"
DO
INPUT "Enter name"; n$
PRINT n$
LOOP UNTIL n$ = "QUIT"END
DisplayHelp:
PRINT "Type QUIT at name prompt."
RETURN
OPEN Statement
OPEN Statement
--------------
Opens a file or device for input or output.
Use:
OPEN filename [FOR access_mode] [ACCESS network_access] [lock_type]
AS [#]file_number [LEN=record_length]
or
OPEN mode, [#]file_number, filename][, record_length]
or
OPEN "COMn: basic_com com_specifics" [FOR access_mode]
AS [#]file_number [LEN=record_length]
* filename is a string expression containing the name
of the file or device to open.
* access_mode specifies how the file is to be used: INPUT,
OUTPUT, APPEND, RANDOM, or BINARY. The default is
RANDOM
* network_access gives more detail on how the file
is to be used in shared-file network environments:
READ, WRITE, or READ WRITE
* lock_type is the type of file locking used in
shared_file envoronments: SHARED, LOCK READ, LOCK
WRITE, or LOCK READ WRITE
* file_number is the integer number to associate
with the file for read, write, and close operations
* record_length is the number of bytes in each record.
For sequential files, the default is 512; for
RANDOM ACCESS files, the default is 128; for
communications, default is 128. Value cannot exceed
32,767.
* mode is used for older Basic programs. It is a
single letter string that specifies the access mode.
Option Mode
A Append
B Binary
I Input
O Output
R Random
* n is the number of the communications port to open,
either 2 or 1.
* basic_com represents the basic data-communications
parameters, seperated by commas, in the following
form:
[baud],[[parity[,[databits][,stopbits]]]]
* baud is baud rate of the device used: 75, 110, 150,
300, 600, 1200, 1800, 2400, 4800, 9600, or 19200
* databits is the number of bits in each data word:
5, 6, 7, or 8. The sum of parity bits and data
bits must be less than or equal to 8. If the
parity is set to O (odd) or E (even), one bit is
used for parity. If parity is set to N (none), no
bits are used for parity.
* stopbits is the number of bits for each word: 1,
1.5, or 2.
* com_specifics is a list of data-communications
specifics, seperated by commas:
ASC Opens device in ASCII mode
BIN Opens device in binary mode
CD(milliseconds) Specifies carrier-detect timeout
CS(milliseconds) Specifies clear-to-send timeout
DS(milliseconds) Specifies data-set-ready timeout
LF Sends linefeed after each carriage return
OP(milliseconds Specifies OPEN statement timeout period
RB(bytes) Specifies the size of the recieve buffer
RS Suppresses detection of request to send (RTS)
TB(bytes) Specifies the size of the transmit buffer
Example:
OPEN "TEST.DAT" FOR INPUT AS #1
f% = FREEFILE
OPEN "NEW.DAT" FOR RANDOM AS f% LEN = 80
OPEN "COM1:4800, E, 7, 1, BIN" AS #2
Related functions: FREEFILE
Related statemnents: CLOSE
OUT Statement
OUT Statement
-------------
Sends a byte to a specific port.
OUT port_number, byte_value
* port_number is an integer expression in the
range 0 through 65,535 that identifies the
port.
* byte_value is an integer expression in the range
0 through 255 to send to the port.
Example:
See INP
Related functions: INP
OPTIONBA Statement
OPTION BASE Statement
---------------------
Sets the default lower array bound.
Syntax:
OPTION BASE {0|1}
Notes:
* If you don't specify a default lower bound,
QBasic uses 0.
* You can specify only one OPTION BASE statement
per module.
* For more flexibility, use the TO clause in the
DIM statement.
ONEXPRES Statement
ON expression Statements
------------------------
Branch to one of several locations based on
the result of an expression.
Syntax:
ON numeric_expression GOSUB location[,location]...
or
ON numeric_expression GOTO location[,location[,location]...
Notes:
* numeric_expression is any mumeric expression
in the range 0 through 255. If necessary,
QBasic rounds the expression to an integer
value.
* location is the list of line numbers or labels to
which control should branch. If the result of the
numeric expression is 1, control branches to the
first location. If the expression is 2, control
branches to the second location, and so on. If
the alue does not have a coorsponding label, the
program continues at the next statement.
Example:
FOR i = 1 TO 3
ON i GOSUB One, Two, Three
NEXT i
END
One:
PRINT "In One"
RETURN
Two:
PRINT "In two"
RETURN
Three:
PRINT "In Three"
RETURN
Related statements: DO UNTIL, DO WHILE, GOSUB, GOTO
PSET Statement
PSET Statement
--------------
Draws a pixel at the specified location
on screen.
Usage: PSET [STEP](x,y)[,color]
Notes:
* The keyword STEP indicates that xa and y are
offsets from the last point drawn, not absolute
coordinates.
* color is the desired pixel color. If you omit
color, PSET usees the current foreground color.
* If the coordinates are outside the current
viewport, no point is drawn.
Example:
CLS
SCREEN 1
DO
PSET (160,100), 0
quad% = INT(RND(1) * 4)
randX% = INT (RND(1) * 10) ' rand num for col movement
randY% = INT [RND(1) * 10) ' rand num for row movement
IF quad% = 0 OR quad% = 3 THEN 'normal movement is to right;
randX% = -randX% ' reverse x value to move left
END IF
FOR i% = 1 TO 20
PSET STEP(-randX% * i%, randY% * i%) ' draw dot
FOR j% = 1 TO DELAY% 'delay loop
NEXT j%
PRESET STEP(0, 0) 'erase dot
NEXT i%
LOOP UNTIL INKEY$ <> ""
PRINT Statement
PRINT Statement
---------------
Writes to screen or sequential file.
Use: PRINT [#file_number,][output_list][{;|,}]
Notes:
* file_number is the number of the file to
which output is written. If you omit it,
QBasic writes the data to the screen.
* output_list is a list of one or more
expressions to output. The expressions
can be string or numeric.
* If a semicolon ends the PRINT statement,
the next PRINT statement continues on the
same line in the next character position.
if instead a comma ends the line, the next
PRINT statement continues on the same line
in the next print zone. Print zones are
14 characters in length. If neither a
semicolon or comma is used to end the line,
the next PRINT statement begins on the
next line.
* If no expression follows the PRINT
command, a blank line is printed to
screen or to the designated sequential
file.
Example:
PRINT "Hello, World!"
Related statements: LPRINT, LPRINT USING,
PRINT USING
PRINTUSE Statement
PRINT USING Statement
---------------------
Writes formatted output to screen or a file.
Usage:
PRINT [#]file_number,] USING format_list; output_list[{;|,}]
POKE Statement
POKE Statement
--------------
Places a byte in the specified memory
location.
Use: POKE offset, byte_value
* offset is the offset--range 0 to 65,535--
within the current segment where you want
to place the byte.
* byte_value is the value (range 0 to 255)
to poke into memory.
* The DEF SEG statement determines the
current segment.
'Fill CGA screen with ASCII 251 (û symbol)
DEF SEG = &HB800
FOR i = 0 TO 3999
IF i MOD 2 = 0 THEN
POKE i, 251 ' check mark or radical symbol
ELSE
POKE i, 7 ' display attribute
END IF
NEXT i
DEF SEG
Related statements: PEEK
Related functions: DEF SEG
PRESET Statement
PRESET Statement
----------------
Draws a pixel at the specified screen
coordinates.
Use: PRESET [STEP](x,y)[,color]
* The keyword STEP indicates that x and y
are offsets from the last point drawn,
as opposed to actual coordinates.
* PRESET is similar to PSET, except that
if you omit color, PRESET uses the
background color.
* If the coordinates are outside the
current viewport, nothing is drawn.
Related functions: POINT
Related statements: CIRCLE, COLOR, DRAW,
LINE, PAINT, PSET
PCOPY Statement
PCOPY Statement
---------------
Copies one video display page to another.
Syntax:
PCOPY source_page, target_page
Notes:
* source_page is an integer expression
that specifies the video display page
to be copied.
* target_page is an integer expression that
specifies the video display page to which
the source page is to be copied..
* The number of video display pages available
is dependent on the video memory size and
video display mode.
Example:
'Copy video page 1 to page 3
PCOPY 1, 3
PAINT Statement
PAINT Statement
---------------
Fills a graphics screen image with the specified
color or pattern.
Syntax:
PAINT[STEP](x,y)[,[{color|tile)][,bordercolor][,background]]]
PUTFILE Statement
PUT Statement (File I/O)
-------------
Writes a random-access file buffer or record
variable to a file.
Syntax:
PUT [#]file_number[,record_number][,variable]]
Notes:
* file_number is the file number assigned to
the file in its OPEN statement.
* record_number is the record number (from 1
through 2,147,483,647) in a random-access
file or the byte offset in a binary file.
* variable is a variable containing the fields
of the record.
Example:
TYPE Employee
ename AS STRING * 20
salary AS SINGLE
END TYPE
DIM emp AS Employee
OPEN "SALARY.DAT" FOR RANDOM AS #1 LEN=LEN(emp)
emp.ename = "Parrish"
em.salary = 50000
PUT #1, 1, emp
CLOSE #1
Related functions: CVD, CDVMBF, CVI, CVL, CVS
CVSMBF, MKD$, MKDMBF$, MKI$, MKL$, MKS$
Related statements: GET, LSET, OPEN, RSET
PEN Statement
PEN Statements
--------------
Enable or disable light pen event trapping.
Syntax:
PEN ON
or
PEN OFF
or
PEN STOP
Notes:
* The PEN ON statement enables light pen
event trapping.
* The PEN OFF statement disables light pen
event trapping.
* The PEN STOP statement temporarily suspends
light pen trapping. All light pen events
occuring during this period are processed
after event trapping is enabled.
Example:
ON PEN GOSUB Handler
PEN ON
Related functions: PEN
Related statements: ON event GOSUB
PUTGRAPH Statement
PUT Statement (Graphics)
------------------------
Displays a graphics image on the screen.
Syntax:
PUT [STEP](x,y),array[(index)][,display_verb]
Notes:
* The keyword STEP indicates that x and y are
offsets from the last point drawn, as opposed
to physical coordinates.
* array is the name of the array containing the
image to display.
* index is the index where the graphics image
begins in the array.
* display_verb indicates how the image is
displayed:
PSET Colors remain uncahnged
PRESET Colors are inverted
AND A logical AND with an existing image
in the same location.
OR A logical OR with an existing image
in the same location.
XOR An exclusive OR of an existing
image on the screen (useful for
animation)
Example:
SCREEN 1
DIM box(1 TO 200)
x1 = 0
x2 = 10
y1 = 0
y2 = 10
LINE (x1,y1)-(x2,y2),2,BF ' create a box
GET (x1,y1)-(x2,y2), box ' save image
FOR i = 1 TO 10000
PUT (x1,y1),box,XOR ' Move box around
x1 = RND * 300 ' screen randomly
y1 = RND * 180
PUT (x1,y1),box
NEXT i
Related statements: GET(Graphics), SCREEN
PLAY Statement
PLAY Statement
--------------
Plays the tune specified by a string
expression.
Syntax:
PLAY string_expression
* string_expression is a string expression
that contains one or more of the following
commands:
Octave commands:
> Increases octave by 1 to a maximum of 6
< Decreases octave by 1 to a minumum of 0
O level Sets the current octave; level must be
0 through 6. Default is 4.
Duration commands:
L notetype Sets the length of each note from 1 to
64; 1 is the whole, 2 is half, and so
on. Default is 4.
ML Sets music legatto
MN Seys music normal
MS Sets music staccato.
Mode Commands:
MF Sets music to foreground. This is the
default.
MB Sets music to background. Up to 32
notes can play as the program executes.
Temp Commands:
P duration Specifies a pause from 1 to 64; 1 is
whole, 2 is half, and so on.
T notes Sets the tempo from 32 to 255. Default
is 120.
Tone Commands:
A-G Playes the note specified.
N note Plays a note from 0 to 84; 0 is a rest.
Suffix commands:
# or + Turns a note into sharp.
- Turns a note into a flat
. Plays the note 3/2 as long as specified.
* The string expression "X+VARPTR$(_string) executes
the music substring _string.
Example:
' Play scale in 7 different octaves
scale$ = "CDEFGAB"
PLAY "L16"
FOR i = 0 TO 6
PLAY "0" + STR$(i)
PLAY "X" + VARPTR$(scale$)
NEXT i
Related functions: PLAY
Related statements: ON event GOSUB, PLAY(Event Trapping),
SOUND
PALETTE Statement
PALETTE Statement
-----------------
Change one or more colors in the color palette.
Syntax:
PALETTE[change_color, new_color]
or
PALETTE USING array[(index)]
Notes:
* change_color is the attribute to change.
* new_color is the new color to assign to
the attribute.
* array is an array of color numbers to
assign to the attributes available in
the current screen mode.
* index is the index of the first element
in the array to use in setting the
palette.
* If you omit all arguments, PALETTE will
restore the default color values.
Example:
PALETTE 0, 1
Related statements: COLOR, SCREEN
PLAYEVEN Statement
PLAY Statements (Event Trapping)
--------------------------------
Enable or disable paly event trapping.
Syntax:
PLAY ON
or
PLAY OFF
or
PLAY STOP
Notes:
* PLAY ON enables play event trapping
* PLAY OFF disables play event trapping.
All events that occur are ignored.
* PLAY STOP temporarily suspends play
event trapping. All play events are
processed after play event trapping
is enabled.
Example:
ON PLAY GOSUB Handler
PLAY ON
Related functions: PLAY
Related statements: ON event GOSUB, PLAY
READ Statement
READ Statement
--------------
Reads values from a data list and assigns them to variables.
Usage: READ variable_list
Notes:
* variable_list is a list of variables seperated by commas.
READ and DATA statements work hand in hand to assign
values to these variables.
Example:
READ n$, age, salary
READ address$
DATA "Kellie", 21, 500
DATA "Las Vegas", Nevada"
PRINT n$, age, salary
PRINT address$
Related statements: DATA, RESTORE
REM Statement
REM statement
-------------
Allows explanatory comments or remmarks
on a program line.
Syntax REM comment
Notes:
* comment is any text
* QBasic ignores comment lines unless they
contain compiler directives.
* QBasic supports the use of a single
quotation mark (') instead of a REM
statement.
* The REM statement must exist on a seperate
line and cannot be appended at the end of
another QBasic statement, unless the colon
is used as a command seperator.
Example:
REM This is a comment
'This is a comment, too.
END ' This is also a comment.
RMDIR Statement
RMDIR Statement
---------------
Removes the specified subdirectory.
Usage: RMDIR directory_name
Notes:
* directory_name is a string expression
containing the name of the directory
to delete.
* RMDIR works like the MS-DOS RMDIR
command. It cannot delete the current
directory or a directory containing
files.
Example:
RMDIR "A:\TEST"
Related statements: CHDIR, MKDIR
RUN Statement
RUN Statement
-------------
Runs the program currently in memory or
an existing program from disk.
Use: RUN[line_number]
or
RUN[file_name]
Notes:
* line_number is a line number in the current
program at which execution should begin.
* file_name is a string expression containing
the name of a file to executes. QBasic
assumes a BAS extension.
* RUN closes all files and erases all variables.
To share variables, use the CHAIN statement.
Example:
RUN "FILENAME"
Related statements: CHAIN
RESET Statement
RESET Statement
---------------
Writes on disk any data still in the file
buffers and closes all disk files.
Use: RESET
* Reset closes all open fils at once. Use
the CLOSE statement to close files
individually.
Example:
RESET
Related statements: CLOSE, OPEN
RETURN Statement
RETURN Statement
----------------
Returns control from a subroutine to the
calling procedure.
Use: RETURN [location]
* location is the line number or label
at which execution should resume. If
you omit location, execution resumes
at the line following the GOSUB
statement or, for event handling, at
the line at which an event occured.
Example:
GOSUB One
GOSUB Two
END
One:
PRINT "In One"
RETURN
Two:
PRINT "In Two"
RETURN
Related statements: GOSUB, ON event GOSUB
RSET Statement
RSET Statement
--------------
Moves data into a random-access file buffer
or right justifies the value of a string
variable.
RSET string_variable = string_expression
* string_variable is either a random-access
file variable or a string variable.
* For random-access file variables, RSET
assigns a record variable of one type to
another.
* For string variables, RSET right-justifies
the string.
Example:
DIM n AS STRING * 10
PRINT "ABCDE"
RSET n = "ABCDE"
PRINT n
Output:
ABCDE
ABCDE
Related statements: FIELD, LSET
RESUME Statement
RESUME Statement
----------------
Continues program execution from an error-trapping
handler.
Usage: RESUME[location]
or
RESUME NEXT
Notes:
* location is the line number or label at which
execution should resume. If you specify 0 or
omit location, execution continues at the
statement causing the error.
* The keyword NEXT continues execution at the
statement immediately following the statement
causing the error.
Example:
ON ERROR GOTO Handler
OPEN "A:TEST.DAT" FOR INPUT AS #1
' code
END
Handler:
PRINT "Place disk containing TEST.DAT"
PRINT "in drive A: Press Enter."
INPUT dummy$
RESUME
Related statements: ERROR, ON ERROR GOTO
REDIM Statement
REDIM Statement
---------------
Cahnges the size of a dynamic array.
Use:
REDIM [Shared] arra(subscripts) AS tpename]
[,array(subscripts)[AS typename]]...
Notes:
* You can change the size of an array but not
the number of dimensions or the data type.
* The keyword SHARED indicates that the array
can be used by all proceedures in the module.
* array is the name of an array to resize
* subscripts specifies the array subscripts
in the form [lowerbound TO] upperbound
* typename is the array type: INTEGER, LONG,
SINGLE, STRING, or user-defined type.
* REDIM erase the array's previous values
Example:
'$DYNAMIC
DIM box (1 TO 100)
'statements
REDIM box (1 TO 200)
Related statements: DIM, ERASE
RESTORE Statement
RESTORE Statement
-----------------
Allow READ to reuse a prevoiusly read DATA statement.
Use: RESTORE [location]
* location is the line number or label of the DATA
statement to read next. If you omit location,
the next READ uses the first DATA statement in
the program.
Example:
FOR i = 1 TO 5
READ a%, b%, c%
PRINT a%, b%, c%
RESTORE
NEXT i
DATA 1, 2, 3
Related statements: DATA, READ
RANDOMIZ Statement
RANDOMIZE Statement
-------------------
Initializes the random number generator
Use: RANDOMIZE[seed]
* seed is an integer expression that
initializes the random number
generator. If you omit seed, your
program will prompt the user to
enter it.
Example:
' print 50 random numers using ten
' different seeds
FOR i = 1 TO 10
PRINT "Seed";
RANDIMIZE i
FOR j = 1 TO 5
PRINT RND
NEXT j
NEXT i
Related functions: RND, TIMER
SELECTCA Statement
SELECT CASE Statement
---------------------
Evaluates an expression and executes the corresponding
block of statements.
Usage: SELECT CASE test_expression
CASE match_expression
[statements]
CASE match_expression
[statements]]
.
.
.
[CASE ELSE
[default statements]]
END SELECT
Notes:
* The SELET CASE statement evaluates an expression
and searches the list of possible ceses for a match. If a
match is found, QBasic executes the statements for that
case.
* test_expression is a string or numeric expression
to evaluate and compare to the possible cases.
* match_expression is an expression to match test_expresion.
It can have the form: expression[,expresion]...
If any of the expressions listed match test_expression,
statements executes.
* match-expression can also take the form of
expresion TO expression
which provides a range of possible values to match.
* Lastly, match expression can have the form
IS relation_operator expression
where relation_operator is <,>,<=,<=,=,or <>
* statements is the list of statements that execute for a
matching case.
* default_statements is the list of statements that execute if
no matching expression is found. These statements are
associated with the CASE_ELSE clause.
* After the statments within a matching case execute, the
program continues execution at the first statement following
the END SELECT statement.
Example:
FOR i = 1 TO 5
SELECT CASE i
CASE 1
PRINT "One"
CASE 2, 3
PRINT "Two or Three"
CASE IS = 4
PRINT "Four"
CASE ELSE
PRINT "Five"
END SELECT
NEXT i
Output:
One
Two or Three
Two or Three
Four
Five
Related statements: IF
SYSTEM Statement
SYSTEM Statement
----------------
Ends the program and returns control to the
operating system.
Suntax: SYSTEM
Notes:
* SYSTEM closes all open files and ends the
program's execution.
* If SYSTEM is not used to end a QBasic program,
QBasic.EXE remains active and no other
programs can be executed without user
interaction.
Example:
SYSTEM
SLEEP Statement
SLEEP Statement
---------------
Suspends program execution for the specified length
of time.
Usage: SLEEP [seconds]
Notes:
* seconds is the number of seconds the program
will be suspended.
* The program remains suspended until the user
presses a key or the specified number of
seconds expires.
* If seconds is omitted or is less than one, the
program suspends indefinately until the user
presses a key or an event currently bing
trapped occurs.
Example:
SLEEP 10
SOUND Statement
SOUND Statement
---------------
Generates a sound from the computer's speaker.
Usage: SOUND frequency, duration
Notes:
* frequency is an integer expression (from
37 to 32,535) that specifies the sound's
frequency in hertz.
* duration is an unsigned integer expression
from 0 through 65,535 that specifies the
length of the sound in clock tics. A clock
tick occurs 18.2 times per second.
Example:
FOR i = 37 TO 3000
PRINT i
SOUND 1, 1
NEXT i
Related functions: PLAY
Related statements: BEEP, PLAY
STOP Statement
STOP Statement
--------------
Ends the program at any point.
Usage: STOP
Example:
Handler:
PRINT "Failed to open file."
STOP
Related statements: SYSTEM
STATIC Statement
STATIC Statement
----------------
Makes the specified variable local to a
subprogram or function and preserves the
variable's value between calls.
Use: STATIC[AS typename][,varible[AS typename]]...
* variable is the name of the variable to make
static.
* typename is the variable type (INTEGER, LONG,
SINGLE, DOUBLE, STRING, or user defined type.
Example:
CALL Test
CALL Test
END
SUB Test
STATIC a AS INTEGER
PRINT a
a = a + 1
END SUB
Output:
0
1
Related statements: COMMON, SHARED
SHELL Statement
SHELL Statement
---------------
Exits program temporarily to execute an
MS-DOS command or batch file.
Use: SHELL [MS-DOS_comand]
* MS-DOS command is a string expression
that specifies the command to run.
When the MS-DOS command is done, the
program proceeds.
* QBASIC creates its own copy of the
environment, so environment variables
created before the program runs may
not be accesible to the SHELL command.
* If you omit the MS-DOS_command, SHELL
displays the MS-DOS prompt, To return
to the program, use the MS-DOS EXIT
command.
Example:
SHELL "DIR /W" ' Display directory listing
SHELL ' MS-DOS prompt
SEEK Statement
SEEK Statement
--------------
Sets the file pointer position for the next
read or write operation.
Use: SEEK [#]file_number, position
* file_number is the file number assigned
to the file in its OPEN statement.
* position is the desired record number in
a random-access file or the byte offset
in a binary or sequencial file. It must
be n the range 1 to 2,147,483,647.
Example:
OPEN "SALARY.DAT" FOR RANDOM AS #1 LEN = 80
SEEK #1, 5 ' move pointer to record 5
Related functions: LOC, SEEK
Related functions: GET(File I/O), OPEN, PUT
SHARED Statement
SHARED Statement
----------------
Gives a subprogram or function access
to module-level variables.
Use:
SHARED variable[AS typename][,variable[AS typename]]...
* By default, a subprogram or function has
access to a variable only if you pass the
variable as a parameter.
* variable is the name of the module-level variable
to share.
* typename is the variable type, e.g., INTEGER
Example:
DIM AS INTEGER
a = 5
CALL TEST
END
SUB Test
SHARED a AS INTEGER
PRINT "Value of variable a is"; a
END SUB
Related statements: DIM
SCREEN Statement
SCREEN Statement
----------------
Defines the screen characteristics.
Use:
SCREEN [screen_mode][,coloroff][,[active_page][,visual_page]]]
* screen mode is an integer expression that
specifies the mode of operation:
Value Mode Adapter
0 Text CGA,EGA,VGA
1 320 x 200 graphics CGA,EGA,VGA,MCGA
2 640 x 200 graphics EGA,VGA
3 720 x 348 graphics Hercules*
4 640 x 400 graphics Olivetti, AT&T 6300
7 320 x 200 graphics EGA,VGA
8 640 x 200 graphics EGA,VGA
9 640 x 350 graphics EGA,VGA
10 640 x 350 graphics EGA,VGA
11 640 x 480 graphics VGA,MCGA
13 320 x 200 graphics VGA,MCGA
(*The Hercules driver MSHERC.COM must be loaded
for screen mode 3)
* color_off is a numeric expression. When true,
it disables color on composite monitors. It
is ignored in screen modes 2 and up.
* active_page is the video display page which
text output and graphics commands write.
* visual_page is the video display page that appears
on your screen.
* visual_page is the video display page that appears
on your screen.
Examople:
SCREEN 1 '320 x 200 graphics
LINE (10,10)-(20,20), , B
Related functions: POINT
Related statements: CIRCLE, COLOR, DRAW, GET(Graphics)
LINE, PAINT, PALETTE USING, PRESET, PSET, PUT(Graphics)
VIEW, WINDOW
SWAP Statement
SWAP Statement
--------------
Syntax:
SWAP variable1, variable2
Notes:
* variable1 and variable2 must be the same
type.
Example:
a = 1
b = 2
SWAP a, b
PRINT a, b
Output from running this program:
2 1
SUB Statement
SUB Statement
-------------
Declares a Basic subprogram.
Syntax:
SUB subprogram_name[(parameter_list)][STATIC]
.
.
.
END SUB
Notes:
* subprogram_name is the base name of the
subprogram (up to 40 characters).
* parameter_list is a list of parameters in
the following form:
variable[()][AS typename][,variable[()][AS typename]]....
* The keyword STATIC directs QBasic to retain
the value of the subprogram's local
variables between calls.
Example:
CALL Test (1, 5.5, "TEST")
END
SUB Test (a AS INTEGER, b AS SINGLE, c AS STRING)
PRINT a, b, c
END SUB
Related statements: CALL, DECLARE, END, EXIT, GOSUB
STRIG Statement
STRIG Statement
---------------
Enable or disable joystick trapping.
Syntax:
STRIG(button) ON
or
STRIG(button) OFF
or
STRIG(button) STOP
* button is a numeric expression that specifies
which joystick button to trap:
Value Traps
0 Lower button on joystick A
1 Lower button on joystick B
4 Upper button on joystick A
6 Upper button on joystick B
* STRIG(button) ON enables joystick trapping
for the specified button.
* STRIG(button) OFF disables joystick trapping
for the specified button. (All events are
ignored)
* STRIG(button) STOP temporarily disables
joystick trapping for the specified button.
Events are processed once trapping is
enabled.
Example:
ON STRIG(0) GOSUB Handler
STRIG(0) ON
Related functions: STRIG
Related statements: ON event GOSUB
TYPE Statement
TYPE Statement
--------------
Creates a user-defined type
Use: TYPE user_typename
element_name AS tpename
.
.
.
END TYPE
Notes:
* user_typename is the name of the user-defined type
* element_name is the name of an element in a record
* typename is the element's type; INTEGER, LONG,
SINGLE, DOUBLE, fixed-length string (e.g.,
STRING * 4), or another user defined type.
* TYPE creates a template for futyre variable
declarations. To create a variable of this type,
you must use DIM, REDIM, COMMON, STATIC, or
SHARED
Example:
TYPE Employee
ename AS STRING * 20
salary AS SINGLE
END TYPE
DIM emp AS Employee
emp.ename = "Stephanie"
emp.salary = 30000
PRINT emp.name, emp, salary
Output of running this program:
Stephanie 30000
Related statements: COMMON, DIM, REDIM, SHARED, STATIC
TRON Statement
TRON Statement
--------------
Enables tracing of statements.
Use: TRON
* See TROFF
Example:
TRON
Related statements: TROFF
TIME$ Statement
TIME$ statement
---------------
Sets the system time.
Syntax:
TIME$ = string_expression
Notes:
* string_expression is a string expression
containing the desired time in the form
"hh:mm:ss" where hh is the hour (0 through
23), mm is the minutes (0 through 59), and
ss is the seconds (0 through 59).
Example:
TIME$ = "12"
TIME$ = "12:30"
Related functions: DATE$, TIME$
Related statements: DATE$
TIMER Statement
TIMER Statement
---------------
Enable or disable timer event trapping.
Syntax:
TIMER ON
or
TIMER OFF
or
TIMER STOP
Notes:
* TIMER ON enables timer event trapping.
* TIMER OFF disables timer event trapping. Timer
events that occur are ignored.
* TIMER STOP temporarily suspends timer event
trapping.
Example:
ON TIMER(10) GOSUB Handler
TIMER ON
DO
LOOP UNTIL INKEY$ <> ""
END
Handler:
PRINT TIME$
RETURN
Related statements: ON event GOSUB
TROFF Statement
TROFF Statement
---------------
Disables tracing of statements.
Syntax:
TROFF
* TROFF and TRON are debugging tools used
by older Basic systems.
Example:
TROFF
Related statements: TRON
UNLOCK Statement
UNLOCK Statement
----------------
Unlocks portions of a shared file for access
by other network programs.
Use:
UNLOCK[#]file_number[,{record | [start] TO end}]
* record is an integer value that specifies a
single record to release in a random-access
file or a single byte to unlock in a binary
file.
* start and end are integer values that specify
the range of record numbers or bytes to unlock.
Example:
OPEN "SHARED.DAT" FOR RANDOM AS #1
LOCK #1, 1 TO 10
'do file update operations
UNLOCK #1, 1 TO 10
CLOSE #1
Related statements: LOCK
VIEW Statement
VIEW Statement
--------------
Defines the screen coordinates within
which graphics can be displayed.
Use:
VIEW [[SCREEN](x1,y1)-(x2,y2)[,fill_color][,border_present]]]
* VIEW allows you to restrict graphics
output to specific coordinates on the
screen. Coordinates outside this
range are not drawn.
* The keyword SCREEN states that graphics
coordinates are relative to the screen,
not the viewport.
* x1 and y1 are the coordinates of one corner
of the viewport; x2 and y2 are the
coordinates of the opposite corner.
* fill_color specifies the color with which
to fill the viewport.
* bordr_present is any numeric expression
that, when present, directs VIEE to draw
a border around the viewport.
* If you omit all arguments, VIEW sets the
viewport to the entire screen.
* The SCREEN and RUN statements set the
viewport back to the entire screen.
Example:
SCREEN 1
VIEW (0,0)-(20-20),1,2
LINE (10,10)-(100,100)
Related staatements: CLS, SCREEn, WINDOW
VIEWPRIN Statement
VIEW PRINT statement
--------------------
Defines the text mode scrolling region.
Use: VIEW PRINT[top_row TO bottom_row]
* top_row and bottom_row are integer
values specifying the top and bottom
rows of the text mode scrolling
region.
* If you omit all arguments, VIEW PRINT
sets the scrolling region to the
entire screen.
Example:
CLS
VIEW PRINT 5 TO 10
FOR i = 1 TO 100
PRINT i, i, i, i
NEXT i
Related statements: CLS, LOCATE, PRINT
WRITE Statement
WRITE Statement
---------------
Writes data to the screen or a sequencial file.
Usage: WRITE[[#]file_number,]expression_list
Notes:
* file_number is the file number assigned to the file in
its OPEN statement. If you omit file_number, QBasic
writes the data to the screen.
* expression_list is a list of one or more variables or
expressions seperated by commas.
* WRITE places a comma between each expression in the
file: the PRINT statement does not.
Example:
OPEN "TEST.DAT" FOR OUTPUT AS #1
WRITE #1, "TEST",5, 3.21, "END"
CLOSE #1
Running this program produces the following result in
TEST.DAT:
"TEST", 5,3.21."END"
Related statements: PRINT
WIDTH Statement
WIDTH Statement
---------------
Sets the number of columns on the screen or
other device or sets the width of a file.
Usage: WIDTH [columns][,lines]
or
WIDTH #file_number, columns
or
WIDTH device_name, columns
or
WIDTH LPRINT columns
Notes:
* columns is the number of columns. The
value must be 40 or 80 for the screen.
* lines is the number of rows of text that
appear on the screen. The value can be
25, 30, 43, 50, or 60, dpending on your
display adapter and current screen mode.
* file_number is the file number assigned
to the file in its OPEN statement.
* device_name is a string expression that
contains the name od the desired device.
* The keyword LPRINT sets the number of
columns for the printer.
* After you specify a width for a device,
output statements automatically wrap
output to the next line when the width
is exceeded.
Example:
'EGA monitor
WIDTH 80, 43
FOR i = 1 TO 100
PRINT i
NEXT i
Related statements: LPRINT, LPRINT USING,
PRINT, PRINT USING, SCREEN
WHILEWEN Statement
WHILE/WEND Statement
--------------------
Repeats a set o instructions as long as a specified
condition is true.
Usage: WHILE condition
statements
WEND
Notes:
* condition is a Boolean expression. As long as
the expression is true, QBasic executes the
statements within the loop.
* statements is any list of statements.
* WHILE/WEND is an older looping consruct. The
use of DO is prefered.
WINDOW Statement
WINDOW Statement
----------------
Defines the logical coordinates for the current
veiwport.
Usage: WINDOW [[SCREEN] (x1,y1)-(x2,y2)]
Notes:
* The keyword SCREEN inverts the screen's
coordinate system such that y values increase
in value from top to bottom of the screen.
* The coordinates x1,y1 and x2,y2 specify the
logical coordinates of the viewport.
Example:
SCREEN 1
WINDOW (0,0)-(50,50)
LINE (10,10)-(40,40),2,8
Related statements: CLS, SCREEN, VIEW
WAIT Statement
WAIT Statement
--------------
Suspends program execution until the
specified pattern is read from the
input port.
Usage: WAIT pprt_number, AND_expression[,XOR_expression]
Notes:
* port_number is an integer expression (from 0 to 255)
that identifies the port.
* AND_expression is an integer expression that WAIT
combines with the port value using an AND
operation.
* XOR_expression is an integer expression that WAIT
combines with the port value using an XOR
operation.
* Data from the specified port is first combined with
XOR_expression if suppied. The result is then combined
with AND_expression . If the result is zero, WAIT
continues reading the port values; otherwise, QBasic
execuutes the next statement.
Example:
WAIT 45, 64
ASC Function
ASC Function
------------
Returns the numeric ASCII code value for the first character
in a string expression.
Usage: ASC(string_expression)
Notes:
* string_expression is any string expression.
Example:
stringvar$ = "ABC"
PRINT ASC(stringvar$)
PRINT ASC("abc")
Running this program will produce the following display:
65
97
Related functions: CHR$
ATN Function
ATN Function
------------
Returns the arctangent of the specified value.
Usage: ATN(numeric_expression)
Notes:
* numeric_expression is the value for which you want to find
the arctangent
* You can express an angle in either degrees or radians.
ATN returns an angle in radians. To convert radians to
degrees, use the following expression:
degrees = radians * (180/3.141593)
Example:
value = TAN(.7854) 'Tangent of pi/4
PRINT "Arctangent is:"; ATN(value)
Output:
Arctangent is .7854
Related functions: COS; SIN; TAN
ABS Function
ABS Function
------------
Returns the absolute value of a numeric expression.
Usage; ABS(numeric_expression)
Notes:
* numeric_expression is any numeric expression.
* ABS always returns a positive value, regardless
of whether the result of the expression is
positive or negative.
* ABS returns a value of the same type as numeric_expression
(integer, long integer, double-precision, and so on).
Example:
PRINT "Absolute value of -3 * 5 is"; ABS(-3 * 5)
PRINT "Absolute value of 3 * 5 is"; ABS(3 * 5)
Running this program produces the following display:
Absolute value of -3 * 5 is 15
Absolute value of 3 * 5 is 15
CHR$ Function
CHR$ Function
-------------
Returns a one-character string containing the character that
corresponds to the specified ASCII value.
Usage: CHR$(ascii_value)
Notes:
* ascii_value is the ASCII code of the desired character
* CHR$ is commonly used to sound the computer bell (CHR$(7)).
* The standard ASCII values range from 0 to 127. IBM clones
and IBM PCs support extended ASCII characters from 128 to 255.
Example:
'Display the ASCII and extended ASCII character sets
FOR i 0 TO 255
PRINT i; CHR$(i)
NEXT i
Related functions: ASC
COMMAND$ Function
COMMAND$ Function
-----------------
Returns the command to be used to invoke the program.
Usage: COMMAND$
Notes:
* This is a QuickBasic command and won't work with QBasic.
* COMMAND$ does not return the name of the program in the
command line.
Example:
' Check to make sure user actually entered something
Line$ = COMMAND$
Length = LEN(line$)
IF Length = 0 THEN
PRINT "Invalid Syntax."
BEEP
END
END IF
'Get the first replaceable parameter
FOR I TO Length
Char$ = MId(Line$,1,1)
IF (Char$<>" " AND CHar$<>(9) AND Char$<>",") THEN
IF First = 0 THEN Build$ = Build$ + Char$
ELSE
First = 1
END IF
NEXT I
PRINT Build$
CINT Function
CINT Function
-------------
Rounds a numeric expression to an integer value.
Usage: CINT(numeric_expression)
Notes:
* numeric_expression must result in a value in the range
-32,768 through 32,767. If the expression is outside this
range, a runtime error occurs.
* CINT rounds; it does not truncate.
Example:
PRINT CINT(34.51)
PRINT CINT(34.49)
Output of this program:
35
34
Related functions: CDBL, CLNG, CSNG
CDBL Function
CDBL Function
-------------
Converts a numeric expression to a double-precision value.
Usage: CDBL(numeric_expression)
Notes:
* numeric_expression is any numeric expression.
* Using CDBL is equivalent to assigning the expression
to a double-precision variable.
* Single-precision values have 7 significant digits.
Double-precision values have 15 significant digits.
Example:
PRINT 5 /6
PRInT CDBL(5 / 6)
Output of this program:
.8333333
.8333333333333334
Related functions: CINT, CLNG, CSNG
COS Function
COS Function
------------
Returns the cosine of the specified angle.
Usage: COS(angle)
CSNG Function
CSNG Function
-------------
Converts a numeric expression to a single-precision
value.
Usage: CSNG(numeric_expression)
CLNG Function
CLNG Function
-------------
Rounds a numeric expression to a long (4-byte) integer.
Usage: CLNG (numeric_expression)
Notes:
* numeric_expression must evaluate to a value in the
range -2,147,483,648 to 2,147,483,647. If the result
is outside this range, a runtime error will occur.
Example:
CVD Function
CVD Function
------------
Converts an eight-byte string (created by MKD$) to
a double precision value.
Usage: CVD(eight_byte_string)
Example:
OPEN "PAYROLL.DAT" FOR RANDOM AS #3 LEN = 35
FIELD #3,27 AS name$, 8 AS salary$
GET #3, 1
PRINT "EMPLOYEE: "; name$
PRINT "SALARY $: "; CVD(salary$)
CLOSE #3
CSRLIN Function
CSRLIN Function
---------------
Returns the current cursor row number.
Usage: CSRLIN
CVDMBF Function
CDVMBF Function
---------------
Converts an eight-byte string containing a
double-precision calue (created by MKDMBF$)
from Microsoft binary format to IEEE format.
Usage: CVDMBF(eight_byte_string)
CVI Function
CVI Function
------------
Converts 2-byte string (created by MKI$) to
an integer value.
Usage: CVI(two_byte_string)
Example:
See CVD
CVL Function
CVL Function
------------
Converts a 4-byte string (created by MKL$)
to a long integer.
Usage: CVL(four-byte-string)
Example:
See CVD
CVS Function
CVS Function
------------
Converts a 4-byte string (created by MKS$)
to a single-precisio, value.
Usage: CVL(four_byte_string)
DATE$ Function
DATE$ Function
--------------
Returns a ten-character string containing the
current system date in the form mm-dd-yyyy.
Usage: DATE$
Example PRINT DATE$
Running this program on January 14, 2004,
produces the following output:
01-14-2004
Related statements: DATE$, TIME$
EOF Function
EOF Function
------------
Tests for the end-of-file condition
Usage: EOF(file_number)
Notes:
* EOF returns true if the end of the file associated with the
file number specified has been reached; otherwise, EOF
returns false.
* file_number is the number assigned to the file in its OPEN
statement.
Example:
OPEN "\CONFIG.SYS" FO INPUT AS #1
DO UNTIL EOF(1)
LINE INPUT #1, fdata$
PRINT fdata$
LOOP
CLOSE #1
Related functions: LOC; LOF
Related statements: CLOSE; OPEN
ERR Function
ERR Function
------------
Returns the error code for the last error
that occured.
Usage: ERR
Notes:
Error Description Error Description
Code Code
1 Next without FOR 6 Overflow
2 Syntax error 7 Out of memory
3 RETURN without 8 Label not defined
GOSUB
4 Out of DATA 9 Subscript out of
range
5 Illegal function call 10 Duplicate definition
11 Division by zero 50 FIELD overflow
12 Illegal in direct 51 Internal error
mode
13 Type mismatch 52 FIELD overflow
14 Out of string space 53 File not found
16 String formula too 54 Bad file mode
complex
17 Cannot continue 55 File already open
18 Function not defined 56 Field statement active
19 No RESUME 57 Device I/O error
20 RESUME without error 58 File already exists
24 Device timeout 61 Disk full
25 Device fault 62 Input past end of file
26 FOR without NEXT 63 Bad record number
27 Out of paper 64 Bad file name
29 WHILE without WEND 67 Too many files
30 WEND without WHILE 68 Device unavailable
33 Duplicate label 70 Permission denied
35 Subprogram not 71 Disk not ready
defined
37 Argument-count 72 Disk media error
mismatch
38 Array not defined 74 Rename accross disks
39 CASE-ELSE expected 75 PATH/FILE access error
40 Variable required 76 Path not found
Example:
See ERL
Related functions: ERDEV, ERDEV$, ERL
Relatd statements: ERROR, ON ERROR GOTO, RESUME
ERL Function
ERL Function
------------
Returns the line number of the statement that
caused the error or the closest line number
before the error-causing statement.
Usage: ERL
Notes:
* ERL returns only line numbers. It does
not return line labels. If you are not
using line numbers, ERL returns 0.
Example:
1010 PRINT "Error processing at line"; ERL
1020 PRINT "Error number" ERR
1030 RESUME
Running this program produces the following
display:
Error processing at line 100
Error number 11
Related functions: ERDEV, ERDEV$, ERR
Related statements: ERROR, ON ERROR GOTO, RESUME
EXP Function
EXP Function
------------
Returns e raised to a psecified power where
e is the base of natural logarithms.
Usage: EXP(numeric_expression)
ERDEV Function
ERDEV Function
--------------
Returns an integer error code from the last
device that declared an error.
Usage: ERDEV
Notes:
* The MS-DOS critical error handler sets
the value for ERDEV. The lower byte
contains the MS-DOS error code (0 to
12). The upper byte contains device
attribute information.
Example:
ON ERROR GOTO Handler
.
.
.
Handler:
PRINT "Error accessing device "; ERDEV$
PRINT "Error status code "; ERDEV
Related functions: ERDEV$. ERL, ERR
Related statements: ERROR, ON ERROR GOTO,
RESUME
ERDEV$ Function
ERDEV$ Function
---------------
Returns the line number of the statement
causing the error or the closest line number
before the error-causing statement.
Notes:
* The MS-DOS critical error handler sets
the value for ERDEV$.
Example:
See ERDEV
Related functions: ERDEV, ERL, ERR
Related statements: ERROR, ON ERROR GOTO,
RESUME
FIX Function
FIX Function
------------
Returns the integer portion of a floating-point
expression.
Usage: FIX(numeric_expression)
Notes:
* numeric_expression is any numeric expression.
Example:
PRINT FIX(-10.99)
PRINT FIX(-10.1)
Output:
-10
-10
Related functions: INT
FRE Function
FRE Function
------------
Returns the amount of available stack space,
string space, or memory.
Usage: FRE(numeric_expression)
or
FRE(string_expression)
Notes:
* If the argument to FRE is -1, FRE returns
the sizes in bytes of the largest array
you can create. If the argument is -2,
FRE returns the available stack space.
For any other numeric argument, FRE returns
the amount of available string space.
* If the argument to FRE is a string
expression, FRE compacts the free string
space into a single block and then re-
turns the available string space.
Example:
PRINT "String space"; FRE("")
PRINT "Stack space "; FRE(-2)
PRINT "Array space "; FRE(-1)
Output:
String space 48460
Stack space 784
Array space 184092
Related statements: CLEAR, ERASE
FREEFILE Function
FREEFILE Function
----------------
Returns the next available Basic file number.
Usage: FREEFILE
Notes:
* FREEFILE obviates the need to hard code file
numbers, and consequently, avoids the danger
of using a file number already in use.
Example:
FileNum = FREEFILE
OPEN "TEST.DAT" FOR INPUT AS FileNum
CLOE FileNum
Related statements: OPEN
FILEATTR Function
FILEATTR Function
-----------------
Returns either the file mode or the MS-DOS
file hanfle for an open file.
Usage: FILEATTR(file_number, file_info)
Notes:
* file_number is the file number assigned to the file
in its OPEN statement.
* file_info dictates the information FILEATTR returns.
IF 1, FILEATTR returns access mode:
Value Mode
-------------
1 Input
2 Output
4 Random
8 Append
32 Binary
* If file_info is 2, FILEATTR returns MS-DOS file
handle.
HEX$ Function
HEX$ Function
-------------
Returns a character string containing the hexadecimal
representation of a value.
Usage: HEX$(numeric_expression)
Notes:
* Hexadecimal notation is the base 16 numbering system. It
uses the numbers 1 through 9 and letters A through F. To
store the hexadeximal representation of a number, you
must use a string variable.
Example:
'Display octal, decimal, and hex values from 0 to 255
FOR i = 0 TO 255
PRINT OCT$(i), i, HEX$(i)
NEXT i
Related functions: OCT$
INSTR Function
INSTR Function
--------------
Returns the location of the first occurance of a string within
another string.
Usage: INSTR([startposition], searchstring, substring)
Notes:
* INSTR returns the character position of substring within
searchstring
* startposition is the character position within searchstring
where the search should begin. If you omit startposition,
INSTR begins at position 1.
* If INSTR locates the substring, it returns an index to the
starting character. Otherwise, INSTR returns 0.
Example:
PRINT "RING in SUBSTRING", INSTR("SUBSTRING", "RING")
PRINT "X in STRING", INSTR("STRING", "X")
Output:
RING in SUBSTRING 6
X in STRING 0
Related functions: LEFT$; LEN; MID$;, RIGHT$
Related statements: MID$
INPUT$ Function
INPUT$ Function
---------------
Reads the specified number of characters from a file or the keyboard.
Usage:
INPUT$(num_charaters[,[#]file_number])
Notes:
* num_characters is the number of characters for INPUT$ to read.
It must be less than or equal to the record length of the
file, which is 128 by default.
* file_number is the number assigned to the file in its OPEN
statement. If you omit a file number, INPUT$ reads from the
keyboard.
Example:
'Display a file in upper case
OPEN "\CONFIG.SYS" OR INPUT AS #1
DO WHILE NOT EOF(1)
char$ = INPUT$(1,1)
PRINT UCASE$(char$);
LOOP
CLOSE #1
Related statements: INPUT; INPUT #, LINE INPUT
INT Function
INT Function
------------
Returns the next integer value smaller than or equal to the
specified numeric expression.
Usage: INT(numeric_expression)
Notes:
* numeric_expression is any numeric expression.
Example:
PRINT INT(99.8), INT(99.1), INT(-99.2)
Output:
99 99 -100
Related functions: FIX
INKEY$ Function
INKEY$ Function
---------------
Reads a character from the keyboard.
Usage: INKEY$
Notes:
* INKEY$ returns a null string if no character is present,
a 1-byte string for standard keys, and a 2-byte string for
extended keys.
* For extended keys, the first character is a null character
(ASCII 0) and the second is the keyboard scan code.
* INKEY$ does not echo the character to the screen.
Example:
PRINT "Press a series of keys - F10 to stop"
DO
DO
k$ = INKEY$
LOOP WHILE k$ = ""
IF LEN(k$) = 1 THEN
PRINT "Letter", k$
ELSE
PRINT "Scan code", ASC(MID$(k$,2,1))
END IF
LOOP UNTIL MID$(k$,2,1) = CHR$(68) 'F10 scan code
INP Function
INP Function
------------
Returns a byte read from an I/O port.
Use: INP(port_number)
Notes:
* port_number is the number associated with
the desired port. It must be in the range
0 through 65,535.
Example:
'Turn on speaker through port 97
saveval = INP(97)
OUT 97, saveval + 3
DO
LOOP WHILE INKEY$ = ""
OUT 97, saveval
Related statements: OUT
IOCTL$ Function
IOCTL$ Function
---------------
Returns a control string from a device driver.
Use: IOCTL$([#]file_number)
Notes:
* file_number is the file number assigned to
the device in its OPEN statement.
* The information IOCTL$ returns is device
dependent. See your hardware documentation
for more information.
Related statements: IOCTL
LTRIM$ Function
LTRIM$ Function
---------------
Removes the leading blank characters from a
string expression.
Usage: LTRIM$(string_expression)
Notes:
* string_expression is any string expression.
Example:
PRINT LTRIM$(" Trim test")
Output:
Trim test
Related functions: RTRIM$
LCASE$ Function
LCASE$ Function
---------------
Returns a character string with all letters
in the specified string expression in lowercase
characters.
Usage: LCASE$(string_expression)
Notes:
* string_expression is any string expression.
Example:
INPUT "Enter a string"; S$
PRINT LCASE$(S$)
Related functions: UCASE$
LEFT$ Function
LEFT$ Function
--------------
Eturns the specified number of characters
beginning from the leftmost character of a
string.
Usage: LEFT$(string_expression,num_char)
Notes:
* string_expression is any string expression.
* num_char is the number of characters to
extrat from the string. It must be in the
range 0 through 32,767.
Example:
s$ = "TEST STRING"
FOR i = 1 TO LEN(s$)
PRINT LEFT$(s$,i)
NEXT i
Related functions: INSTR, LEN, MID$, RIGHT$
Related statements: MID$
LEN Function
LEN Function
------------
Returns the number of characters in a string
or the number of bytes used to store a
variable.
Usage: LEN(string_expression)
or
LEN(variable
Notes:
* string_expression is any string expression.
* variable is any variable of a type other than
STRING.
Example:
DIM x AS INTEGER
a$ = "13 CHARACTERS"
PRINT a$, LEN(a$)
PRINT "Integer"; LEN(x), "Long"; LEN(y)
Output:
13 CHARACTERS 13
Integer 2 Long 4
Related functions: INSTR, LEFT$, MID$, RIGHT$
Related statements: MID$
LOF Function
LOF Function
------------
Returns the number of bytes in a file.
Usage: LOF(file_number)
Notes:
* file_number is the file number assigned
to the file in its OPEN statement.
* You cannot use LOF with devices.
Example:
OPEN "\CONFIG.SYS" FOR INPUT AS #1
PRINT "File size in bytes is"; LOF(1)
CLOSE #1
LBOUND Function
LBOUND Function
---------------
Returns the lowest array subscript for the
specified array dimension.
Usage: LBOUND(array_name)[,dimension]
Notes:
* array_name is the name of the array of
interest.
* dimension is an integer value specifying
the dimension of interest in a multi-
dimensional array.
Example:
DIM a(50 TO 100) AS INTEGER
DIM box(1 TO 3, 3 TO 6) AS INTEGER
PRINT LBOUND(a)
PRINT LBOUND(box, 1), LBOUND(box, 2)
Output:
50
1 3
Related functions: UBOUND
Related statements: DIM
LOG Function
LOG Function
------------
Returns the natural logarithm of a numeric
expression.
Usage: LOG(numeric_expression)
Notes:
* numeric_expression is any numeric expression
greater than 0.
* The natural logarithm is the logarithm to
the base e.
Example:
PRINT LOG(1), LOG(EXP(1))
Output:
0 1
Related functions: EXP
LOC Function
LOC Function
------------
Returns the current offset or record number
within a file.
Usage: LOC(file_number)
Notes:
* file_number is the file number assigned in the
file's OPEN statement.
* For binary files, LOC returns the current byte
offset in the file. For random access files,
LOC returns the current record number. For a
sequencial file, LOC returns the current offset,
divided by 128. For a COM device, LOC returns
the number of bytes in the input queune.
Example:
IF LOC(<) < 100 THEN CALL ReadIt(salary)
Related functions: SEEK
Related statements: SEEK
LPOS Function
LPOS Function
-------------
Returns the current position of the printer
head wirhin a print buffer.
Usage: LPOS(printer_number)
Notes:
* printer number is the number of the printer
of interest, where 1 is LPt1, 2 is LPT2,etc.
* Not all printers uspport LPOS
MID$ Function
MID$ Function
-------------
Returns a substring of a string expression that begins at the
specified offset location.
Usage: MID$(string_expression, start_offset[,length])
Notes:
* sting_expression is any string expression
* start_offset is the position of the first character of the
subtring
* length is the number of characters in the substring. If you
omit length, MID$ returns all characters from the start_offset
through the end of the string.
Example:
a$ = "ABCDEFGHI"
PRINT MID$(A$, 1, 5)
PRINT MID$(A$, 6)
Output:
ABCDE
FGHI
Related functions: INSTR; LEFT$; LEN; RIGHT$
Related statements: MID$
MKD$ Function
MKD$ Function
-------------
Converts a double-precision value to an
8-byte string for output to a random-access
file by PUT.
Useage: MKD$(numeric_expression)
MKDMBF$ Function
MKDMBF$ Function
----------------
Converts a double-precision value stored in IEEE
format to an 8-byte string containing the value
in Microsoft binary format for output to a
random-access file by PUT.
Syntax:
MKDMBF$(numeric_expression)
MKI$ Function
MKI$ Function
-------------
Converts an integer value to a 2-byte
string for output to a random-access
file by PUT.
Syntax:
MKI$(numeric_expression)
MKL$ Function
MKL$ Function
-------------
Converts a long integer value to a 4-byte
string for output to a random-access file
by PUT.
Syntax:
MKL$(numeric_expression)
* numeric_expression is a long integer
numeric expression.
MKS$ Function
MKS$ Function
-------------
Convers a single-precision value to a 4-byte
string for output to a random_access file by
PUT.
Syntax:
MKS$(numeric_expression)
MKSMBF$ Function
MKSMBF$ Function
----------------
Converts a single-precision value stored in
IEEE format to a 4-byte string containing the
value in Microsoft binary format for output
to a random_access file by PUT.
Syntax:
MKSMBF$(numeric_expression)
OCT$ Function
OCT$ Function
-------------
Returns a string ontaining the octal representation
of an integer expression.
Usage: OCT$(numeric_expression)
Notes:
* Octal is the base-8 numbring system.
* numeric_expression is any numeric expression.
Example:
See HEX$
Related funtions: HEX$
POS Function
POS Function
------------
Returns the cursor column position.
Usage: POS(dummy_argument)
Notes:
* POS does not use the parameter dummy_argument.
Example:
FOR i = 1 TO 100
IF (POS(0) > 50) THEN
PRINT i
ELSE
PRINT i; ' same line
END IF
NEXT i
Related functions: CSRLN, LPOS
Related statements: LOCATE
PEEK Function
PEEK Function
-------------
Returns the byte stored at a specific memory
offset.
Use: PEEK(offset)
* offset is an integer expression--range 0
through 65,535) that specifies an offset
within the current default segment as
defined by the DEF SEG statement.
Example:
'Save the screens contents
DIM screensave(3999) AS INTEGER
DEF SEG = &HB800
FOR i 0 TO 3999
screensave(i) = PEEK(i)
NEXT i
DEF SEG
Related statements: DEF SEG, POKE
PMAP Function
PMAP Function
-------------
Maps a physical coordinate to a logical
coordinate defined by the WINDOW statement
or vice versa.
Syntax:
PMAP(coordinate,mapping)
POINT Function
POINT Function
--------------
Returns a pixel's color or coordinates.
Syntax:
POINT(x,y)
or
POINT(mapping)
PEN Function
PEN Function
-------------
Returns light pen coordinates.
Syntax:
PEN(numeric_expression)
Notes:
* numeric_expression is an integer value
In the range 0 to 9) that specifies
the information PEN returns:
0 -1 if pen used since last call; otherwise, 0
1 The x pixel coordinate where pen was last pressed
2 The y pixel coordinate where pen was last pressed
3 Current usage: -1 if down, 0 if up
4 The last known x pixel value
5 The last known y pixel value
6 Character row where pen was last pressed
7 Character column where pen was last pressed
8 The last known character row
9 The last known character column
* PEN does not work when a mouse driver is active.
Example:
row% = PEN(6)
colun% = PEN(7)
PLAY Function
PLAY Function
-------------
Returns the number of notes in the background
music queune.
Syntax:
PLAY(dummy_argument)
* Dummy_argument is any numeric argument.
It distinquishes the PLAY function from
the PLAY statement.
* PLAY returns 0 when music is in foreground
mode.
Example:
notes% = PLAY(0)
Related statements: ON event GOSUB, PLAY,
PLAY (Event Trapping), SOUND
RTRIM$ Function
RTRIM$ Function
---------------
Removes trailing spaces from a string expression.
Usage:
RTRIM$(string_expression)
Notes:
* string_expression is any string expression
Example:
a$ = "AAAA "
b$ = "BBBB"
PRINT RTRIM$(a$); b$
Running this program produces the following display:
AAAABBBB
Related functions: LTRIM$
RND Function
RND Function
------------
Returns a single random number between 0 and 1.
Use: RND[(numeric_expression)]
Notes:
* numeric_expression specifies how RND generates
the next random number:
Value Generates
-------------------------------------------------
Less than zero The same number for any given
numeric_expression
Equal to 0 The last number generated
Greater than zero The next ramdom number
* If you omit numeric_expression, RND generates
the next number in the sequence.
Example:
'Print ten random numbers
FOR i = 1 TO 10
PRINT INT(RND * 10))
NEXT i
Related statements: RANDOMIZE
RIGHT$ Function
RIGHT$ Function
---------------
Returns the specified number of characters
from the rightmost characters in a string.
Usage: RIGHT$(string_expression, num_char)
Notes:
* string_expression is any string expression.
* num_char is the number of characters to
return. If num_char exceedes the length of
the string, RIGHT$ returns the entire
string.
Example:
A$ = "ABCDEFGHIJ"
FOR I 1 TO 10
PRINT RIGHT$(A$, I)
NEXT I
Related functions: INSTR, LEFT$, LEN, MID$
SEEK Function
SEEK Function
-------------
Returns the current file pointer position.
Usage: SEEK(file_number)
Notes:
* file_number is the file number assigned
to the file in its OPEN statement.
* For random-access files, SEEK returns a
record number in the range 1 through
2,147,483,647. For binary and sequencial
files, SEEK returns the current byte
offset.
Example:
position = SEEK(1)
Related functions: LOC
Related statements: OPEN, SEEK
SGN Function
SGN Function
------------
Returns a value indicating the sign of an expression.
Usage: SGN(numeric_expression)
* If the alue of the expression is negative, SGN
returns -1. If the value is positive, SGN will
return 1. If the value is 0, SGN returns 0.
Example:
PRINT SGN(-6)
PRINT SGN(0)
PRINT SGN(12)
Output:
-1
0
1
STRING$ Function
STRING$ Function
----------------
Returns a string containing the specified
number of occurances of a character.
Use: STRING$(num_char, ascii_character)
or
STRING$(num_char, string_expression)
Notes:
* num_char is the desired number of occurances
of a character.
* ascii_character is the ASCII code of the
character.
* string_expression is any string expression.
If you provide a string, STRING$ uses the
first character of the string.
Example:
a$ = STRING$(20, 64)
PRINT a$
STR$ Function
STR$ Function
-------------
Returns the string representation of a numeric
expression.
Use: STR$(numeric_expression)
Notes:
* numeric_expression is any numeric expression
Example:
x$ = STR$(4.2892)
PRINT x$
Related functions: VAL
SPACE$ Function
SPACE$ Function
---------------
Returns a string containing the specified
number of spaces.
Use: SPACE$(num_spaces)
Notes:
* num_spaces is an integer expression from
0 up to 32,767.
Example:
FOR i = 0 TO 3
PRINT SPACE$(i); i
NEXT i
Output:
0
1
2
3
Related functions: SPC, TAB
SPC Function
SPC Function
------------
Skips the specified number of spaces in a
PRINT or LPRINT statement.
Use: SPC(num_spaces)
Notes:
* num_spaces is an nteger value no larger
than 32,767.
Example:
FOR i = 0 TO 5
PRINT SPC(i); i
NEXT i
Related functions:
SPACES$, TAB
SQR Function
SQR Function
------------
Returns the square root of an expression
Use: SQR(numeric_expression)
Notes:
* numeric_expression is any non-negative numeric
expression.
Example:
FOR i = 0 TO 100
PRINT i, SQR(i)
NEXT i
SIN Function
SIN Function
------------
Returns the sine of the specified angle.
Use: SIN(angle)
* angle is a numeric expression that
specifies an angle in radians.
* Angles can be expressed in radians or
degrees. QBasic supports only radians.
To convert from degrees to radians,
use the equation:
radians = 3.141593 * (degrees / 180)
Example:
pi = 3.141593
PRINT "Sine of pi", SIN(pi)
Related statements:
ATN, COS, TAN
STICK Function
STICK Function
--------------
Returns a joystick's x or y coordinate.
Use: STICK(numeric_expression)
Notes:
* numeric_expression is an unsigned integer
in the range 0 through 3 that specifies
the desired value:
0 x coordinate of joystick A
1 y coordinate of joystick A
2 x coordinate of joystick B
3 y coordinate of joystick B
* x and y coordinates can range from 1 to 200
Example:
x% = STICK(0)
y% = STICK(1)
STRIG Function
STRIG Function
--------------
Returns the value of the joystick trigger.
Use: STRIG(numeric_expression)
* numeric_expression is an unsigned integer
from 0 through 7 to specify the type of
information desired:
Value Condition
0 lower joystick A button pressed since last STRIG(0)
1 lower joystick A button currently pressed
2 lower joystick B button pressed since last STRIG(2)
3 lower joystick B button currently pressed
4 upper joystick A button pressed since last STRIG(4)
5 upper joystick A button currently pressed
6 upper joystick B button pressed since last STRIG(6)
7 upper joystick B button currently pressed
* If the specified condition is true, STRIG returns -1, else
STRIG returns 0.
Example:
' wait for user to press lower button of joystick A
DO
LOOP UNTIL STRIG(0)
Related statements: ON event GOSUB; STRIG
SCREEN Function
SCREEN Function
---------------
Returns the character or the color attribute
for the character at the specified row and
column.
Use: SCREEN(row,column[get_color])
* row and column are the coordinates of the
character
* get_color is a numeric expression. If
get_color is 1, SCREEN returns the color
of the character. If get_color is 0 or
is omitted, SCREEN returns the ASCII alue
of the character at the specified
location.
Example:
DIM scr(1 TO 25, 1 TO 80) AS INTEGER
'Store current screen contents
FOR row = 1 TO 25
FOR column = 1 TO 80
scr(row, column) = SCREEN(row, column)
NEXT column
NEXT row
TAN Function
TAN Function
------------
Returns the tangent of a specified angle.
Usage: TAN(angle)
Notes:
* angle is a numeric expression that evaluates
to an angle in radians.
* The QBasic trigonometric routines support only
radians, not degrees, to express an angle. To
convert from degrees to radians use:
radians = 3.141593 * (degrees / 180)
Example:
pi = 3.141593
PRINT TAN(pi / 4)
Related functions: ATN, COS, SIN
TAB Function
TAB Function
------------
Moves the print position to the specified
column.
Usage: TAB(column)
Notes:
* column is the desired tab column. If
the current position is beyond the
specified column, TAB moves to the
column on the next line.
Example:
For i = 1 TO 10
PRINT TAB(i); i
NEXT i
Related Functions: SPC
TIME$ Function
TIME$ Function
--------------
Returns the current time in an eight character
string of the form hh:mm:ss.
Usage: TIME$
Example:
PRINT TIME$
Example output:
12:00:00
Related functions: DATE$
Related statements: DATE$, TIME$
TIMER Function
TIMER Function
--------------
Returns the number of seconds since midnight.
Syntax:
TIMER
Notes:
* You can use TIMER with RANDOMIZE to seed
the random number generator.
Example:
RANDOMIZE TIMER
UBOUND Function
UBOUND Function
---------------
Returns the highest array subscript for the
specified array dimension.
Usage: UBOUND(array_name[,dimension])
Notes:
* array_name is the name of the array of
interest.
* dimension is an integer value specifying
the dimension of interest in a multi-
dimensional array. The default is 1.
Example:
DIM a(1 TO 5, 1 TO 10, 1 TO 25)
PRONT UBOUND(a), UBOUND(a, 2), UBOUND(a, 3)
Output:
5 10 25
Related functions: LBOUND
Related statements: DIM, OPTION BASE, REDIM
UCASE$ Function
UCASE$ Function
---------------
Returns a character string with letters in
the specified string in uppercase.
Usage: UCASE$(string_expression)
* string_expression is any string expression.
Example:
a$ = cZcd$F
PRINT UCASE(a$)
Output:
CZCD$F
Related functions: LCASE$
VAL Function
VAL Function
------------
Converts a string representation of a numeric
value to the actual numeric value.
Usage: VAL(string_expression)
Notes:
* string_expression is the string representation
of a numeric value.
* VAL stops at the first character it cannot
recognize as part of a number. Valid characters
are 0 through 9, the period, the minus sign,
and the plus sign.
Example:
PRINT VAL("33.44")
PRINT VAL("88k")
Output:
33.44
88
Related functions: STR$
VARSEG Function
VARSEG Function
---------------
Returns a variable's segment in memory.
Use: VARSEG(variable)
* variable is the name of any variable
in the program.
Example:
See CALL ABSOLUTE
Related functions: VARPTR
Related statements: DEF SEG
VARPTR Function
VARPTR Function
---------------
Returns a variable's offset in memory.
Use: VARPTR(variable)
* variable is the name of any variable
in the program.
* QBasic does not guarantee that a variable
will reside in the same memory location
throughout the program execution. So use
VARPTR immediately before any code that
uses the offset value.
Example:
See CALL ABSOLUTE
Related functions: VARSEG
Related statements: DEF SEG
VARPTR$ Function
VARPTR$ Function
----------------
Returns a string representation of a variable's
offset for use in the PLAY and DRAW statements.
Use: VARPTR$(string_variable)
* string_variable is a string variable
containing DRAW or PLAY commands.
* QBasic does not guarantee that a variable
will reside in the same memory location
throughout the program execution. So use
VARPTR immediately before any code that
uses the offset value.
Example:
scale$ = "CDEFGAB"
PLAY "X" + VARPTR$(scale$)
Related statements: DRAW, PLAY