HP 3000 Manuals HP 3000 Manuals
PERFORM
Transfers control to a labeled statement.
Syntax
PERFORM label;
PERFORM transfers execution to the statement identified by label.
Execution continues until one of the following is encountered:
RETURN Returns control to the statement immediately following the
corresponding PERFORM statement.
END Specifies the end of the current processing level and returns
control to the previous processing level, or to command level
if no previous processing level is active within the perform
block.
another Specifies the end of the current command sequence. The
label compiler generates an END statement and the effect is the same
as END.
PERFORM statements can be nested up to a maximum of 75 levels. Note that
this differs from PERFORM= options in data management verbs, which allow
a maximum of 10 levels of nesting. Although GO TO statements can branch
into and out of PERFORM statement loops, this is not generally good
coding practice.
Statement Parts
label The label that identifies the sequence of statements called by
PERFORM.
Examples
When the response to INPUT causes a transfer to the label ADD-IT, the
statements between ADD-IT and RETURN execute. Control then returns to
the PROMPT statement that immediately follows the IF statement.
IF INPUT = "YES", "Y" THEN
PERFORM ADD-IT
ELSE GO TO GET-ACCT;
PROMPT INV-NUM("Invoice Number"), RIGHT;
:
END;
ADD-IT:
PUT CUST-FILE, LIST=(NAME:ZIP);
LET (NUM) = (NUM) + 1;
DISPLAY NAME, COL=5, NOHEAD:
"HAS BEEN ADDED TO CUSTOMER FILE.", JOIN;
RETURN;