Using IF to Control Multiple Statements
executes multiple statements under the control of the IF tests at lines 004000 and 004400. In each sequence, a PERFORM is requested to display an additional message before the main message is displayed. More than one statement can be executed when an IF tests true:
IF condition
PERFORM DO-SOMETHING
PERFORM DO-SOMETHING-ELSE.
An IF controls all statements under it until the sentence ends. When an IF tests true, all statements up to the next period are executed. When an IF tests false, all statements up to the next period are skipped.
TYPE: Listing 4.3. Controlling multiple statements with IF.
000100 IDENTIFICATION DIVISION.
000200 PROGRAM-ID. YESNO03.
000300*--------------------------------------------------
000400* This program asks for a Y or N answer, and then
000500* displays whether the user chose yes or no.
000600* The edit logic allows for entry of Y, y, N, or n.
000700*--------------------------------------------------
000800 ENVIRONMENT DIVISION.
000900 DATA DIVISION.
001000 WORKING-STORAGE SECTION.
001100
001200 01 YES-OR-NO PIC X.
001300
001400 PROCEDURE DIVISION.
001500 PROGRAM-BEGIN.
001600
001700 PERFORM GET-THE-ANSWER.
001800
001900 PERFORM EDIT-THE-ANSWER.
002000
002100 PERFORM DISPLAY-THE-ANSWER.
002200
002300 PROGRAM-DONE.
002400 STOP RUN.
002500
002600 GET-THE-ANSWER.
002700
002800 DISPLAY "Is the answer Yes or No? (Y/N)".
002900 ACCEPT YES-OR-NO.
003000
003100 EDIT-THE-ANSWER.
003200
003300 IF YES-OR-NO IS EQUAL "y"
003400 MOVE "Y" TO YES-OR-NO.
003500
003600 IF YES-OR-NO IS EQUAL "n"
003700 MOVE "N" TO YES-OR-NO.
003800
003900 DISPLAY-THE-ANSWER.
004000 IF YES-OR-NO IS EQUAL "Y"
004100 PERFORM IT-IS-VALID
004200 DISPLAY "You answered Yes.".
004300
004400 IF YES-OR-NO IS EQUAL "N"
004500 PERFORM IT-IS-VALID
004600 DISPLAY "You answered No.".
004700
004800 IT-IS-VALID.
004900 DISPLAY "Your answer is valid and".
005000
OUTPUT:
Is the answer Yes or No? (Y/N)
y
Your answer is valid and
You answered Yes.
C>
C>
ANALYSIS: When the IF at line 004400 tests true, lines 004100 and 004200 are executed, one after the other. Line 004100 is a PERFORM request that causes a message to be displayed at line 004900. A similar action happens when the IF at line 004000 tests true and lines 004500 and 004600 are executed.
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