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COBOL - Loop Statements
COBOL - Loop Statements
There are some tasks that need to be done over and over again pke reading each record of a file till its end. The loop statements used in COBOL are −
Perform Thru
Perform Until
Perform Times
Perform Varying
Perform Thru
Perform Thru is used to execute a series of paragraph by giving the first and last paragraph names in the sequence. After executing the last paragraph, the control is returned back.
In-pne Perform
Statements inside the PERFORM will be executed till END-PERFORM is reached.
Syntax
Following is the syntax of In-pne perform −
PERFORM DISPLAY HELLO WORLD END-PERFORM.
Out-of-pne Perform
Here, a statement is executed in one paragraph and then the control is transferred to other paragraph or section.
Syntax
Following is the syntax of Out-of-pne perform −
PERFORM PARAGRAPH1 THRU PARAGRAPH2
Example
IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. PROCEDURE DIVISION. A-PARA. PERFORM DISPLAY IN A-PARA END-PERFORM. PERFORM C-PARA THRU E-PARA. B-PARA. DISPLAY IN B-PARA . STOP RUN. C-PARA. DISPLAY IN C-PARA . D-PARA. DISPLAY IN D-PARA . E-PARA. DISPLAY IN E-PARA .
JCL to execute the above COBOL program.
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS = A,MSGCLASS = C //STEP1 EXEC PGM = HELLO
When you compile and execute the above program, it produces the following result −
IN A-PARA IN C-PARA IN D-PARA IN E-PARA IN B-PARA
Perform Until
In ‘perform until’, a paragraph is executed until the given condition becomes true. ‘With test before’ is the default condition and it indicates that the condition is checked before the execution of statements in a paragraph.
Syntax
Following is the syntax of perform until −
PERFORM A-PARA UNTIL COUNT=5 PERFORM A-PARA WITH TEST BEFORE UNTIL COUNT=5 PERFORM A-PARA WITH TEST AFTER UNTIL COUNT=5
Example
IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-CNT PIC 9(1) VALUE 0. PROCEDURE DIVISION. A-PARA. PERFORM B-PARA WITH TEST AFTER UNTIL WS-CNT>3. STOP RUN. B-PARA. DISPLAY WS-CNT : WS-CNT. ADD 1 TO WS-CNT.
JCL to execute the above COBOL program −
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS = A,MSGCLASS = C //STEP1 EXEC PGM = HELLO
When you compile and execute the above program, it produces the following result −
WS-CNT : 0 WS-CNT : 1 WS-CNT : 2 WS-CNT : 3
Perform Times
In ‘perform times’, a paragraph will be executed the number of times specified.
Syntax
Following is the syntax of perform times −
PERFORM A-PARA 5 TIMES.
Example
IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. PROCEDURE DIVISION. A-PARA. PERFORM B-PARA 3 TIMES. STOP RUN. B-PARA. DISPLAY IN B-PARA .
JCL to execute the above COBOL program −
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS = A,MSGCLASS = C //STEP1 EXEC PGM = HELLO
When you compile and execute the above program, it produces the following result −
IN B-PARA IN B-PARA IN B-PARA
Perform Varying
In perform varying, a paragraph will be executed till the condition in Until phrase becomes true.
Syntax
Following is the syntax of perform varying −
PERFORM A-PARA VARYING A FROM 1 BY 1 UNTIL A = 5.
Example
IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-A PIC 9 VALUE 0. PROCEDURE DIVISION. A-PARA. PERFORM B-PARA VARYING WS-A FROM 1 BY 1 UNTIL WS-A=5 STOP RUN. B-PARA. DISPLAY IN B-PARA WS-A.
JCL to execute the above COBOL program −
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS = A,MSGCLASS = C //STEP1 EXEC PGM = HELLO
When you compile and execute the above program, it produces the following result −
IN B-PARA 1 IN B-PARA 2 IN B-PARA 3 IN B-PARA 4
GO TO Statement
GO TO statement is used to change the flow of execution in a program. In GO TO statements, transfer goes only in the forward direction. It is used to exit a paragraph. The different types of GO TO statements used are as follows −
Unconditional GO TO
GO TO para-name.
Conditional GO TO
GO TO para-1 para-2 para-3 DEPENDING ON x.
If x is equal to 1, then the control will be transferred to the first paragraph; and if x is equal to 2, then the control will be transferred to the second paragraph, and so on.
Example
IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-A PIC 9 VALUE 2. PROCEDURE DIVISION. A-PARA. DISPLAY IN A-PARA GO TO B-PARA. B-PARA. DISPLAY IN B-PARA . GO TO C-PARA D-PARA DEPENDING ON WS-A. C-PARA. DISPLAY IN C-PARA . D-PARA. DISPLAY IN D-PARA . STOP RUN.
JCL to execute the above COBOL program:
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS = A,MSGCLASS = C //STEP1 EXEC PGM = HELLO
When you compile and execute the above program, it produces the following result:
IN A-PARA IN B-PARA IN D-PARAAdvertisements