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jeelagahema
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Joined: 12 Jun 2005
Posts: 12
Location: bangalore
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| why we will use comp-3 declaration? |
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jsk
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Joined: 20 Feb 2006
Posts: 12
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Hi Jeelagahema,
COMP-3 enables the computer to store two digits in each storage position, except for the rightmost position, which holds the sign. Suppose if you move 1234567 into a field defined 9(7). In DISPLAY mode, which is default, this field will use 7 storage positions.
If you define the field with PIC 9(7) COMP-3, it will however use only four positions
12 34 56 7+
We can save a significant amount of storage by using the USAGE-COMP-3
Please correct me if I am wrong |
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raghunathns
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Joined: 08 Dec 2005
Posts: 127
Location: rochester
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you have to check the file status after each read
end of file.. do not process.. terminate program. |
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DavidatK
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Joined: 22 Nov 2005
Posts: 700
Location: Troy, Michigan USA
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jeelagahema,
| Quote: |
| why we will use comp-3 declaration? |
Just a subscript to what jsk posted. Along with the space savings that is present with COMP-3, it is also easier to read on a program dump than COMP or display, and it is more efficient for the processor than display. If you look at the object code produced by a arithmetic operation, you will fine that the complier converts display fields to COMP-3, does the operation and then converts back to display back to display. The hardware is designed to do the arithmetic operations with COMP-3 or COMP (binary), but not display fields.
Dave |
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hncs
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Joined: 01 Mar 2006
Posts: 11
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IF WE USE COMP-3 THEN THE EFFICIENCY IS MORE. AND MORE OVER IT WILL TAKE VERY LESS MEMORY COMPARED WITH DISPLAY.
COMP-3 IS NOTHING BUT PACKED DECIMAL VALUE.
SUPPOSE IF THE FIELD SIZE IS S9(N)
IF N IS EVEN THEN IT WILL TAKE (N+2)/2 BYTES.
IF N IS ODD THEN IT WILL TAKE (N+1)/2 BYTES.
FOR EACH DIGIT IT WILL TAKE HALF BYTE AND HALF BYTE FOR SIGN. |
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