KR edition 158 to 159

 

KR-158 : COBOL Puzzle- idea contributed by Jeyakumar

 

Hi everyone,

 

We have a COBOL puzzle for this edition...

WS-EMP-ID is a PIC X(8) working storage variable and the following snippet is executed. What is the output?

MOVE SPACES TO WS-EMP-ID
IF WS-EMP-ID > 0 
     DISPLAY 'SPACE > 0!' 
ELSE 
     DISPLAY 'SPACE <=0!' 
END-IF

MOVE '11111111' TO WS-EMP-ID 
IF WS-EMP-ID > 0 
     DISPLAY 'EMP ID > 0!' 
ELSE 
     DISPLAY 'EMP ID <= 0!' 
END-IF  

It's something that generally confuses a programmer!

 Another question is will WS-EMP-ID > 0 compile?

  Yes it will and the answer is:
             SPACE <=0!
             EMP ID > 0!

Puzzled? Do you know why?  

         We'll ponder into the explanation in the next edition! Stay tuned..

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KR-159 : COBOL puzzle explanation

 

We start off the week with the explanation for the previous COBOL puzzle contributed by Jeyakumar:

• A zero as a character is represented as hex F0 (based on EBCDIC coding). 

• Any number stored as a character (i.e. in PIC X format), say n, is represnted as hex Fn in EBCDIC format. 

• Thus when any number stored in character format is compared with character 0, the number will be greater. Which is why in the puzzle we got EMP ID > 0! for the following snippet:

             MOVE '11111111' TO WS-EMP-ID 
             IF WS-EMP-ID > 0 
                  DISPLAY 'EMP ID > 0!' 
            ELSE 
                  DISPLAY 'EMP ID <= 0!' 
            END-IF 

(character 1 in hex is F1 and character 0 is hex F0; so F1 > F0 and thus EMP ID > 0 is displayed).

• The character space is represented by hex 40 (which is the same value used in ASCII coding scheme as well). So the snippet:  

           MOVE SPACES TO WS-EMP-ID
           IF WS-EMP-ID > 0 
                DISPLAY 'SPACE > 0!' 
           ELSE 
                DISPLAY 'SPACE <=0!' 
           END-IF 

will yield the result SPACE <=0 because character space is hex 40 while 0 is represented as F0 (and hex 40 is < hex F0).