The evaluate logic helps you to avoid multiple if statements in your program. This also avoids confusion in understanding COBOL logic.
We already know the syntax for evaluate is:
When other in Evaluate..
Why “when other ” you need to mention in evaluate -the reason is very simple:
To avoid ambiguity to the compiler, you need to mention it.
The other way is , if the conditions are not matched, it helps what action to take.
One more point is, during validations for Numeric or character, you may get scenario like spaces – so to handle spaces what action it should take you need to mention the when other condition.