MODULE 7: COBOL Control statements
- This is simplest form of PERFORM statement. It is used to execute specified paragraph, and on completion of paragraph execution, control is returned back to the next statement following PERFORM
PERFORM para-nameWhere, para-name is paragraph you want to execute
In PROCUEDURE DIVISION,PARA-0. DISPLAY ‘IN PARA-0’. PERFORM PARA-1. DISPLAY ‘RETURNED FROM PARA-1’. STOP RUN. PARA-1. DISPLAY ‘IN PARA-1’.
- In above example, program first starts by executing first instruction of PARA-0, then since PERFORM is coded it will call PARA-1, once all instruction from PARA-1 is executed, control will be returned back to the next instruction following PERFORM and thus, in SYSOUT we can see ‘RETURNED FROM PARA-1’ is displayed. Above example is also demonstrated in flow chart form below.
SYSOUT display (output):-
IN PARA-0 IN PARA-1 RETURNED FROM PARA-1
Using PERFORM statement versus GO TO statement
In case if we had used GO TO in place of PERFORM then flow would be like:-GO TO:-Since GO TO is used, control is not returned back and thus, statements coded in PARA-0 after GO TO will remain unexecuted