Coding a choice of actions

Use IF . . . ELSE to code a choice between two processing actions. (The word THEN is optional.) Use the EVALUATE statement to code a choice among three or more possible actions.

About this task


IF condition-p
  statement-1
ELSE
  statement-2
END-IF

When one of two processing choices is no action, code the IF statement with or without ELSE. Because the ELSE clause is optional, you can code the IF statement as follows:


IF condition-q
  statement-1
END-IF

Such coding is suitable for simple cases. For complex logic, you probably need to use the ELSE clause. For example, suppose you have nested IF statements in which there is an action for only one of the processing choices. You could use the ELSE clause and code the null branch of the IF statement with the CONTINUE statement:


IF condition-q
  statement-1
ELSE
  CONTINUE
END-IF

Note: NEXT SENTENCE can be very different from CONTINUE, based on location of the following period, as shown in this example:

IF condition-r
  statement-1
ELSE
  CONTINUE or NEXT SENTENCE
END-IF
*> CONTINUE goes to statement-2
  statement-2
  statement-3.
*> NEXT SENTENCE goes to statement-4
  statement-4

For details about NEXT SENTENCE, see IF statement in the Enterprise COBOL for z/OS® Language Reference.

The EVALUATE statement is an expanded form of the IF statement that allows you to avoid nesting IF statements, a common source of logic errors and debugging problems.