In this topic, we described about the below sections -
Iterative programming construction involves making the set of statements runs in repetitive/iterative/looping manner. In iterative programming construction, the statements execute repeatedly until the specified condition is true. The PERFORM statement is the part of the iterative programming construction.
PERFORM Statement -
PERFORM statement executes the set of statements/block of statements repetitively. The repetitive execution can be conditional or unconditional. If any condition specified, the statements block gets executed until the specified condition is true.
The END-PERFORM used to end the scope of the in-line PERFORM statement. Execution of an in-line PERFORM statement is completed after executing the END-PERFORM statement.
END-PERFORM statement is optional if the statements under PERFORM is ended with period. The period considers as a logical end of PERFORM statement.
PERFORM Types -
PERFORM statement is mainly two types –
- In-line PERFORM
- Out-of-line PERFORM
The below table describes the differences between in-line an out-of-line PERFORM statements –
|In-line PERFORM||Out-of-line PERFORM|
|The PERFORM statement executes the implicit statement that coded in between PERFORM and END-PERFORM||The PERFORM statement transfers control explicitly to one or more procedures|
|Not required to transfer the control explicitly||Control explicitly transfers to the procedures|
|Not required to specify any procedure||Procedures must specify in PERFORM statement|
|Mainly used to perform a set of statements/ block of statements that executed in between the PERFORM and END-PERFORM||Mainly used to perform set of statements/ block of statements coded in separate section or separate paragraph or procedure|
|Scope terminator END-PERFORM is mandatory that represents the end of PERFORM statements||Scope terminator END-PERFORM is not required|
The in-line and out-of-line PERFORM formats can’t be combined. If procedure-name-1 is specified, imperative statements and the END-PERFORM phrase must not be specified. If procedure-name-1 is not specified, imperative statements and END-PERFORM phrase must be specified.
Different PERFORMs -
The PERFORM statement formats are -
|Simple PERFORM||Used to execute the statements-block/procedures|
|THROUGH PERFORM||Used to execute the statements-block that are coded with procedure|
|TIMES phrase PERFORM||Used to execute statements-block/procedures number of times specified|
|UNTIL phrase PERFORM||Used to execute the statements-block/paragraph until the specified condition true|
|VARYING phrase PERFORM||Used to execute the statements-block/procedures by increasing or decreasing the values of one or more identifiers for the iterations|