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saubhik
New User
Joined: 21 Sep 2007
Posts: 35
Location: kolkata
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| Difference between Based and define in PL1. |
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Srihari Gonugunta
Active User
Joined: 14 Sep 2007
Posts: 295
Location: Singapore
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You can use the DEFINED attribute to overlay variable storage,
but DEFINED overlay the storage permanently.
When based variables are overlaid with a locator reference, the association can be changed at any time in the program by assigning a new value to the locator variable.
Thanks,
Sri Hari G. |
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saubhik
New User
Joined: 21 Sep 2007
Posts: 35
Location: kolkata
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| It would be great if you can give some example. |
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Garry Carroll
Senior Member
Joined: 08 May 2006
Posts: 1193
Location: Dublin, Ireland
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Here's a couple of samples.
The first code snippet shows use of DEFINED where the record-area is a variable within the program. RECORD_AREA1 and the DEFINED variable are in a fixed location.
| Code: |
DCL RECORD_AREA1 CHAR(80) INIT(' ');
DCL R1_DEFINED_BYTE_10 CHAR(10) DEF RECORD_AREA1;
READ FILE (FILE1) INTO(RECORD_AREA1);
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whereas the second snippet shows overlaying (redefining) on a relocatable . The READ SET statement relocates the structure to the record in the I/O buffer. The BASED(ADDR(FIELD1)) is also relocated. This cannot be done with DEFINED.
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DCL 1 RECORD_AREA2 BASED(PTR2),
3 FIELD1 CHAR(10),
3 FIELD2 CHAR(70);
DCL R2_OVERLAY CHAR(10) BASED(ADDR(FIELD1));
READ FILE(FILE2) SET(PTR2); |
Regards,
Garry. |
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