GWBASIC User's Manual

GW-BASIC User's Guide
OPEN Statement
Purpose:
To establish input/output (I/O) to a file or device.
Syntax:
OPEN mode,[#]file number,filename[,reclen]
OPEN filename [FOR mode][ACCESS access][lock] AS [#]file number
[LEN=reclen]
Comments:
filename is the name of the file.
mode (first syntax) is a string expression with one of the following characters:
Expression Specifies
O Sequential output mode
I Sequential input mode
R Random input/output mode
A Position to end of file
mode (second syntax) determines the initial positioning within the file, and the action to be taken
if the file does not exist. If the FOR mode clause is omitted, the initial position is at the beginning
of the file. If the file is not found, one is created. This is the random I/O mode. That is, records
may be read or written at any position within the file. The valid modes and actions taken are as
follows:
INPUT Position to the beginning of the file. A "File not found" error is given if the
file does not exist.
OUTPUT Position to the beginning of the file. If the file does not exist, one is created.
APPEND Position to the end of the file. If the file does not exist, one is created.
RANDOM Specifies random input or output mode.
mode must be a string constant. Do not enclose mode in double quotation marks. access can be
one of the following:
READ
WRITE
READ WRITE
file number is a number between 1 and the maximum number of files allowed. The number
associates an I/O buffer with a disk file or device. This association exists until a CLOSE or CLOSE
file number statement is executed.
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