Controlling loops is very common in COBOL. For that COBOL has 6 top performs. The six types include viz: perform-times, perform -until, Perform-After, Perform-Varying, Inline Perform, and Perform-thru.
6 Types of COBOL Perform Statements
The perform statement continues till the end of end-perform you can say as in-line perform. When the perform calls another para, you can say as outline perform.
1). COBOL Inline Perform
Perform procedure-name-1 end-perform.
2). COBOL perform thru
Perform procedure-name-1 thru procedure-name-2.
3). COBOL perform n times
Perform procedure-name N times.
4). COBOL perform until condition
Perform procedure-name-1 thru procedure-name-2 until <condition>
5). COBOL perform thru varying
Perform procedure-name-1 thru procedure-name-2 varying identifier-1/index-name-1 From identifier2/index-name-2/literal-1 By identifier-3/literal-2 Until <condition>.
6). COBOL perform from by option using varying
Perform procedure-name-1 thru procedure-name-2
By Identifier-6/Literal-4 UNTIL <condition-2>.