Opening optional files
If a program tries to open and read a file that does not exist, normally an error occurs.
About this task
However,
there might be times when opening a nonexistent file makes sense.
For such cases, code the keyword OPTIONAL
in the SELECT
clause:
SELECT OPTIONAL file ASSIGN TO filename
Whether
a file is available or optional affects OPEN
processing,
file creation, and the resulting file status key. For example, if
you open in EXTEND
, I-O
, or INPUT
mode
a nonexistent non-OPTIONAL
file, the result is an OPEN
error,
and file status 35 is returned. If the file is OPTIONAL
,
however, the same OPEN
statement returns file status
05, and, for open modes EXTEND
and I-O
,
creates the file.
Related references
File status key (COBOL for Linux® on x86 Language Reference)
OPEN statement notes (COBOL for Linux on x86 Language Reference)
File status key (COBOL for Linux® on x86 Language Reference)
OPEN statement notes (COBOL for Linux on x86 Language Reference)