Paragrafe și PERFORM

In COBOL, modularity and logical structuring of code inside the PROCEDURE DIVISION do not occur via functions or methods, but rather through Paragraphs and the PERFORM statement.

Defining Paragraphs

A paragraph is a labeled section of code starting with a name at column 8 (Area A) ending with a period ., followed by a sequence of instructions at column 12 (Area B).

DISPLAY-MESSAGE.
    DISPLAY "This is a paragraph!".

Paragraphs allow splitting potentially very long programs into reusable and self-documenting blocks.

Executing Paragraphs with PERFORM

The PERFORM statement invokes and executes a paragraph, then returns control to the instruction immediately following the PERFORM statement.

PROCEDURE DIVISION.
MAIN-PROCEDURE.
    DISPLAY "Starting program...".
    PERFORM PROCESS-DATA.
    DISPLAY "Ending program.".
    STOP RUN.

PROCESS-DATA.
    DISPLAY "Processing data in memory...".

In the above listing:

1. The DISPLAY inside MAIN-PROCEDURE is executed.
2. PERFORM PROCESS-DATA branches execution to the PROCESS-DATA paragraph.
3. Once the PROCESS-DATA paragraph ends, execution returns to MAIN-PROCEDURE to print "Ending program." and halt using STOP RUN..

Try it yourself