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Computing statement truncation


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sivasaras

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Joined: 29 Sep 2007
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Location: chenna/i-

PostPosted: Tue Jan 06, 2015 9:33 pm
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Hi,

I have a compute statement in my cobol code.

A PIC X(02)

MOVE 32 TO A.

C PIC 9(2)

COMPUTE C = 16 * A

value is 512 but it is storing the value as 12 not 51.

please help me how to store the first 2 numbers.

Thanks
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David Robinson

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PostPosted: Tue Jan 06, 2015 9:54 pm
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So you just want the 51 to be stored, ignoring the 2 ???
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Robert Sample

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PostPosted: Tue Jan 06, 2015 9:56 pm
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If the PIC clause is too small to hold the result, COBOL aligns to the decimal point (whether explicit or implicit). Your C variable has an implicit decimal point after the second digit, hence the 12 will be stored and the 5 dropped. The easiest way to capture the 51 would be to define C as PIC 9(03) and then REDEFINE a variable on C that is PIC X(02).
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Terry Heinze

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PostPosted: Tue Jan 06, 2015 10:42 pm
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It can be dangerous using a PIC X (alphanumeric) field in a calculation. I'd either redefine it as numeric, or better yet, define A as numeric. Also, read very carefully the section in the Programming Language Manual about the precision of intermediate results when using the COMPUTE statement. COBOL doesn't do what you might expect it to.
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Bill Woodger

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PostPosted: Tue Jan 06, 2015 11:02 pm
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How did you use a PIC X(2) as a source field in a COMPUTE?

Why would you expect 51 to be the answer? I'm not sure I know of any programming language which right-truncates results to fit in a field.

For an answer, you can also truncate your result by dividing by 10. Not normally something I recommend, but since you are multiplying by 16 already, why don't you multiply instead by 1.6?

Terry,

It obviously took me 20 minutes to type that amongst other things. The PIC X definition for A will cause the compiler to upchuck and refuse to even attempt the COMPUTE.

COMPUTE works exactly how it should work. The problem people have with COMPUTE is that they don't read the intermediate results section that you suggested. They tend to think of a computer as a big calculator, or something which uses numbers-of-unlimited-size-and-unlimited-decimal-places-even-though-it-can't-do-decimal-calculations-accurately-in-all-cases.
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Rohit Umarjikar

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PostPosted: Thu Jan 08, 2015 3:42 am
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Quote:
value is 512 but it is storing the value as 12 not 51


Red Alram--> Is it a bug or a requirement? if bug then simply increase the size of C otherwise use the above methods as suggested.
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