Using Compaq COBOL in the Alpha Common Language Environment
13.4 Calling Routines
For example:
01 SS$_NORMAL PIC S9(5) COMP VALUE EXTERNAL SS$_NORMAL
.
.
.
CALL "LIB$STAT_TIMER" USING ARG-CODE, ARG-VALUE GIVING RET-STATUS.
IF RET-STATUS NOT EQUAL SS$_NORMAL...
Because all success codes have odd values, you can check a return status for any
success code. For example, you can cause execution to continue only if a success
code is returned by including the following statement in your program:
IF RET-STATUS IS SUCCESS ...
Sometimes several success condition values are possible. You may only want to
continue execution on specific success codes.
For example, the $SETEF system service returns one of two success values:
SS$_WASSET or SS$_WASCLR.If you want to continue only when the success
code SS$_WASSETis returned, you can check for this condition value as follows
and branch accordingly:
IF RET-STATUS EQUAL SS$_WASSET ...
or
EVALUATE RET-STATUS
WHEN SS$_WASSET ...
If the condition value returned is not a success condition, then the routine did not
complete normally,and the information it should have returned may be missing,
incomplete, or incorrect.
Youcan also check for specific error conditions as follows:
WORKING-STORAGE SECTION.
01 USER-LINE PIC X(30).
01 PROMPT-STR PIC X(16) VALUE IS "Type Your Name".
01 OUT-LEN PIC S9(4) USAGE IS COMP.
01 COND-VALUE PIC S9(9) USAGE IS COMP.
88 LIB$_INPSTRTRU VALUE IS EXTERNAL LIB$_INPSTRTRU.
.
.
.
PROCEDURE DIVISION.
P0. CALL "LIB$GET_INPUT" USING BY DESCRIPTOR USER-LINE PROMPT-STR
BY REFERENCE OUT-LEN
GIVING COND-VALUE.
EVALUATE TRUE
WHEN LIB$_INPSTRTRU
DISPLAY "User name too long"
WHEN COND-VALUE IS FAILURE
DISPLAY "More serious error".
.
.
.
13–14 Using Compaq COBOL in the Alpha Common Language Environment