段落とパフォーマンス

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).

Code

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.

Code

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:

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

Try it yourself

運動#cobol.m3.l1.e1

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Define a paragraph named DISPLAY-TOTAL that prints 'TOTAL IS DONE' using DISPLAY, and call it inside MAIN-PROCEDURE using PERFORM before stopping the program.

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Write PERFORM DISPLAY-TOTAL. at column 12, and below the MAIN-PROCEDURE block declare the DISPLAY-TOTAL. paragraph at column 8.

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運動#cobol.m3.l1.e2

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Call two paragraphs sequentially, first INITIALIZE-DATA and then PROCESS-DATA, within the MAIN-PROCEDURE block.

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Insert the two PERFORM statements in sequential order at column 12.

3 回の試行後に解決策が利用可能になります