CSC1140, Introduction to COBOL, ChanJin Chung

Ch 8_2. IF (II)

Nested IF

Consider the following decision table.

   Condition        Condition           Action
   ---------        ---------          ----------
    A = B             C = D            Perform X1

    A = B          C NOT EQUAL TO D    Perform X2

A NOT EQUAL TO B      anything         Perform X3


IF A = B
   IF C = D
      PERFORM X1
   ELSE
      PERFORM X2
   END-IF
ELSE
   PERFORM X3
END-IF

Compound Conditions

OR & AND can be used to combine conditions. Example:

IF HUSBAND-PAY > 50000 AND WIFE-PAY > 50000
   PERFORM MORE-TAX-RTN
END-IF

 Order of Evaluation 
AND are evaluated first from left to right then conditions surrounding
OR are evaluated.
IF A = B AND C > D OR E < F 
   PERFORM XXX
END-IF

Which routine will be performed?
MOVE 7 TO A.
MOVE 6 TO B.
MOVE 8 TO C.
IF A = 7 AND B = 5 OR C = 8
   PERFORM X
ELSE
   PERFORM Y 
END-IF