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VMS Help IF, Examples *Conan The Librarian |
1.$ COUNT = 0
$ LOOP:
$ COUNT = COUNT + 1
.
.
.
$ IF COUNT .LE. 10 THEN GOTO LOOP
$ EXIT
This example shows how to establish a loop in a command
procedure, using a symbol named COUNT and an IF statement.
The IF statement checks the value of COUNT and performs an EXIT
command when the value of COUNT is greater than 10.
2.$ IF P1 .EQS. "" THEN GOTO DEFAULT
$ IF (P1 .EQS. "A") .OR. (P1 .EQS. "B") THEN GOTO 'P1'
$ WRITE SYS$OUTPUT "Unrecognized parameter option ''P1' "
$ EXIT
$ A: ! Process option a
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.
.
$ EXIT
$ B: ! Process option b
.
.
.
$ EXIT
$ DEFAULT: ! Default processing
.
.
.
$ EXIT
This example shows a command procedure that tests whether a
parameter was passed. The GOTO command passes control to the
label specified as the parameter.
If the procedure is executed with a parameter, the procedure
uses that parameter to determine the label to branch to. For
example:
@TESTCOM A
When the procedure executes, it determines that P1 is not null,
and branches to the label A. Note that the EXIT command causes
an exit from the procedure before the label B.
3.$ SET NOON
.
.
.
$ LINK CYGNUS,DRACO,SERVICE/LIBRARY
$ IF $STATUS
$ THEN
$ RUN CYGNUS
$ ELSE
$ WRITE SYS$OUTPUT "LINK FAILED"
$ ENDIF
$ EXIT
This command procedure uses the SET NOON command to disable
error checking by the command procedure. After the LINK
command, the IF command tests the value of the reserved global
symbol $STATUS. If the value of $STATUS indicates that the LINK
command succeeded, then the program CYGNUS is run. If the LINK
command returns an error status value, the command procedure
issues a message and exits.
4.$ if 1 .eq. 1
$ then
$ if 2 .eq. 2
$ then
$ write sys$output "Hello!"
$ endif
$ endif
This example shows how to use a nested IF structure.
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