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Compress an alphanumeric character

 
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gauravgupta01

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PostPosted: Wed Jan 15, 2014 2:39 pm    Post subject: Compress an alphanumeric character
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Hi,

I have a problem where in I need to pack an alphanumeric string to save some space.

For example the below string -

Code:


ABCDEF
CCCCCC
123456



I need to convert it in -

Code:


¿òÕ
ACE
BDF



Is this kind of conversion possible in cobol? Keeping in mind that I can use upto A to F alphanumeric characters.

Any help would be much appreciated.
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sureshpathi10

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PostPosted: Wed Jan 15, 2014 3:09 pm    Post subject:
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Hello,

Are you really asking a COBOL program to compress a data set, so you can save some spaces?

or

Do you want to convert a string to another based on some logic ?
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gauravgupta01

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PostPosted: Wed Jan 15, 2014 3:20 pm    Post subject:
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Hi Suresh,

I am just looking to compress the data to save space.
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Bill Woodger

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PostPosted: Wed Jan 15, 2014 3:23 pm    Post subject: Reply to: Packing an alphanumeric character
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It can be done, of course. It would seem unlikely that you have sufficient quantity of text with only A-F to make it worthwhile. Perhaps if you explain fully what is going on you can get some suggestions.
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sureshpathi10

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PostPosted: Wed Jan 15, 2014 3:25 pm    Post subject:
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You can use 'Z' command in front of the data set in 3.4 option.

or

Code:

                   Data Set List Actions                   
                                                           
Data Set: dataset.name.here                               
                                                           
DSLIST Action                                             
    1.  Edit                     14. Print Index           
    2.  View                     15. Reset                 
    3.  Browse                   16. Move                 
    4.  Member List              17. Copy                 
    5.  Delete                   18. Refadd               
    6.  Rename                   19. Exclude               
    7.  Info                     20. Unexclude 'NX'       
    8.  Short Info               21. Unexclude first 'NXF'
    9.  Print                    22. Unexclude last 'NXL' 
    10. Catalog                  23. SuperC 'SC'           
    11. Uncatalog                24. SuperCE 'SCE'         
    12. Compress                 25. Search-For 'SF'       
    13. Free                     26. Search-ForE 'SFE'     


choose option 12 for compress.

Is that different from what are you looking for?
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steve-myers

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PostPosted: Wed Jan 15, 2014 3:43 pm    Post subject:
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sureshpathi10 wrote:
You can use 'Z' command in front of the data set in 3.4 option. ...
The Z option in ISPF DSLIST is intended to "compress" PDS data sets.

While you are in ISPF EDIT, there is a PACK option that will "compress" the data when it is saved. However, once the data set has been saved, its contents are effectively unreadable by other programs unless they know how to expand the data to its original format. The ISPF edit PACK option performs what is known in the trade as a "run length encoded" compression; for typical text data the "packed" data set is roughly 1/2 the size of the source data set.

The compression you originally proposed will cause the source data to be unreadable.
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sureshpathi10

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PostPosted: Wed Jan 15, 2014 3:52 pm    Post subject:
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Thanks Steve... I didn't know this trick.

Here is what I found out with HELP icon_biggrin.gif

Code:

TUTORIAL ----------------- EDIT - 'PACK' COMMAND --------------------- TUTORIAL
COMMAND ===>                                                                   
                                                                               
  Use the PACK command to turn PACK mode on or off ("on" is the default) and   
  save the mode setting in the edit profile.  If PACK mode is on when the     
  data is saved (via a SAVE or END command), the data will be written to the   
  disk in "packed" format.  If PACK mode is off the data will be written in   
  standard format.                                                             
                                                                               
        Command ===> pack                 data will be "packed" when written   
                                            (back) to the library or file.     
        Command ===> pack off             data will be written in standard     
                                            format.                           
                                                                               
  Packed data is automatically "unpacked" when read in for editing.  Whether   
  or not the data is stored in packed format is transparent to you while       
  editing data (except as indicated by the profile lines).                     
                                                                               
  Packing of data is intended to save DASD space.                             
                                                                               
  SCLM supplied parsers do not recognize packed data.  PACK mode must be off   
  when data is saved in order for SCLM supplied parsers to generate accurate   
  statistics.


But it showing ("on" is the default) ?
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steve-myers

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PostPosted: Wed Jan 15, 2014 5:47 pm    Post subject:
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sureshpathi10 wrote:
... But it showing ("on" is the default) ?
When you enter PACK as a primary command the effect is the same as PACK ON. I'm pretty sure that's what the meaning of the help text you copied here.

ISPF PACK is not often used because it renders the data unusable to most other programs.

Several years ago there was talk about eliminating it, but that talk died away shortly afterwards.
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enrico-sorichetti

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PostPosted: Wed Jan 15, 2014 7:26 pm    Post subject: Reply to: Packing an alphanumeric character
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before PACKING things
ask the powers of Your organization ...
a packed anything might break the current behavior of some/few/many JCLs
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sureshpathi10

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PostPosted: Wed Jan 15, 2014 7:37 pm    Post subject:
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Hi Steve,

When 'PACK' is already on as it is given default... there is no use of using it again rt?

So gauravgupta01 can not use this command for his requirement.
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dick scherrer

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PostPosted: Wed Jan 15, 2014 7:48 pm    Post subject:
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Hello,

Neither compressing nor packing will do what is wanted.

Possibly a better explanation of the data will help someone provide help.

What kind of data would have alpha fields that only had values from A thru F?
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sureshpathi10

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PostPosted: Wed Jan 15, 2014 7:54 pm    Post subject:
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Yeah Dick, You are right....

as far as I know, only Hex values would be 0..9..A...F
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gauravgupta01

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PostPosted: Thu Jan 16, 2014 9:32 am    Post subject:
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Hi All,

Thank you so much for taking time out and helping me. Actually pack is not the option I was looking for since this would render my code unusable. What I am looking is to pack a specific variable.

I have a task to convert an assembler program into a cobol one and PACK is one of the commands being used in there to pack the variable (I believe they must have done it to save some register space) however the logic has been built around the packed parameter and would require changes to a lot of places hence I was looking for an option in cobol which would do this conversion.
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sureshpathi10

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PostPosted: Thu Jan 16, 2014 10:18 am    Post subject:
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Are you planning to store these values after conversion, like in a table or file ?

Anyway, As you mentioned in the example.

Your input is:
Code:
ABCDEF

your expecting output is:
Code:

¿òÕ
ACE
BDF


This reminding me of converting HEX to CHAR. You must consider every two Characters as a HEX value and convert into CHAR.

You can search thru internet for "how to convert HEX to CHAR in cobol", you may get many examples. if you can't find any, we will help you out.

Hope this helps icon_smile.gif
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gauravgupta01

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PostPosted: Thu Jan 16, 2014 10:30 am    Post subject:
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Agreed with hex conversion but how to push the hex value in a nibble is the problem i am thinking.
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gauravgupta01

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PostPosted: Thu Jan 16, 2014 10:40 am    Post subject:
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Thanks All. I guess i found the answer. So silly of me but thanks to all of you.

Found the answer here -

http://ibmmainframeforum.com/viewtopic.php?f=6&t=9019
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dick scherrer

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PostPosted: Thu Jan 16, 2014 9:41 pm    Post subject:
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Hello,

You have not yet explained just what this data is.

Long ago (40+ yrs) when i used the PACK instruction it was for taking a zoned decimal number and putting the value in a packed decimal field. Currently the bible (Principles of Operations) says the same thing.

So i am lost with this request/requirement icon_confused.gif

If you explain what is in the field and the rules for the content of the field, someone here will be able to help.
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gauravgupta01

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PostPosted: Fri Jan 17, 2014 3:24 pm    Post subject:
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The input data is containing numeric as well as alphanumeric characters. Digits can be 0-9 and Alphanumeric can be A-F. Since it was a fairly large x(256) variable hence it was being compressed in a packed format to be contained in X(128) variable.
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dick scherrer

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PostPosted: Fri Jan 17, 2014 7:45 pm    Post subject:
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Hello,

This still does not explain why/how there is a data field that contains only 0-9, A-F. What kind of data is this?

I have never seen a "data field" that is limited to that set of values. What are the other fields in the record?
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Bill O'Boyle

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PostPosted: Fri Jan 17, 2014 9:38 pm    Post subject: Reply to: Packing an alphanumeric character
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Here's a COBOL sub-program (CHAR2HEX), which will convert from 01 to 30 Bytes of Display-Numeric and Letters A-F into a packed-format.

The compiler option ARITH(EXTEND) must be specified during compilation (as illustrated).

So, for example, you pass a value of '0123456789ABCDEF' in the 31-position character (display) parm (ensure it's padded with low-order EBCDIC zeros), it will be returned in the packed-decimal parm as XL16'0123456789ABCDEF000000000000000F'.

Code:

CBL LIST,NOOFFSET,OPT(FULL),NOTEST,TRUNC(OPT),ARITH(EXTEND),FLAG(I,I)   
       IDENTIFICATION DIVISION.                                         
      ******************************************************************
      *----------------------------------------------------------------*
      *                                                                *
      *    THIS SUB-PROGRAM IS 'CALLED', PASSING THE FOLLOWING -       *
      *                                                                *
      *    03  WS-CHAR2HEX        PIC  X(08)       VALUE 'CHAR2HEX'.   *
      *    03  WS-CHAR2HEX-PARM-REC.                                   *
      *        05  WS-CHAR2HEX-PARMIN-X.                               *
      *            07  WS-CHAR2HEX-PARMIN                              *
      *                           PIC  9(18).                          *
      *            07  FILLER     PIC  X(13).                          *
      *        05  WS-CHAR2HEX-PARMOUT-X.                              *
      *            07  WS-CHAR2HEX-PARMOUT                             *
      *                           PIC  9(16)V9     PACKED-DECIMAL.     *
      *            07  FILLER     PIC  X(07).                          *
      *        05  WS-CHAR2HEX-RETURN-CODE                             *
      *                           PIC  9(02).                          *
      *                                                                *
      *     CALL WS-CHAR2HEX          USING WS-CHAR2HEX-PARM-REC.      *
      *                                                                *
      *     THE VALUE PASSED IN 'PARMIN-X' MUST BE LEFT-JUSTIFIED, UP  *
      *     TO 30-BYTES. BYTE-31 IS USED BY THIS SUB-PROGRAM AS A      *
      *     'GARBAGE' BYTE AND WILL BE OVERWRITTEN.                    *
      *                                                                *
      *     MOVE ZERO                  TO WS-CHAR2HEX-PARMIN-X.        *
      *     MOVE '0123456789ABCDEF'    TO WS-CHAR2HEX-PARMIN-X (1:16). *
      *                                                                *
      *     AFTER THE 'CALL', THE 'PARMOUT-X' VALUE WILL BE -          *
      *     XL16'0123456789ABCDEF000000000000000F'                     *
      *                                                                *
      *     NOTE: ALL NUMERICS MUST BE DEFINED _WITHOUT_ A SIGN. ALSO, *
      *     THIS SUB-PROGRAM MUST BE COMPILED, USING THE ARITH(EXTEND) *
      *     COMPILER OPTION, AS NOTED IN THE 'CBL' CARD.               *
      *                                                                *
      *----------------------------------------------------------------*
      ******************************************************************
       PROGRAM-ID. CHAR2HEX.                                           
       ENVIRONMENT DIVISION.                                           
       DATA DIVISION.                                                   
       WORKING-STORAGE SECTION.                                         
       LINKAGE SECTION.                                                 
       01  LS-CHAR2HEX-PARM-REC.                                       
           03  LS-DISPLAY-X.                                           
               05  LS-DISPLAY-V9   PIC  9(30)V9.                       
           03  LS-PACKED-X.                                             
               05  LS-PACKED-V9    PIC  9(30)V9    PACKED-DECIMAL.     
           03  LS-RETURN-CODE-X.                                       
               05  LS-RETURN-CODE  PIC  9(02).                         
       PROCEDURE DIVISION USING LS-CHAR2HEX-PARM-REC.                   
           MOVE ZERO                   TO LS-DISPLAY-X                 
                                              (LENGTH OF LS-DISPLAY-X:).
      *                                                                 
           MOVE 1                      TO TALLY.                       
           MOVE ZERO                   TO LS-RETURN-CODE-X.             
      *                                                                 
           PERFORM UNTIL TALLY > LENGTH OF LS-DISPLAY-X                 
               IF (LS-DISPLAY-X (TALLY:1) NOT < ZERO                   
               AND LS-DISPLAY-X (TALLY:1) NOT > '9')                   
               OR (LS-DISPLAY-X (TALLY:1) NOT < 'A'                     
               AND LS-DISPLAY-X (TALLY:1) NOT > 'F')                   
                   NEXT SENTENCE                                       
               ELSE                                                     
                   MOVE ZERO           TO LS-DISPLAY-X (TALLY:1)       
                   IF  LS-RETURN-CODE-X = ZERO                         
                       MOVE TALLY      TO LS-RETURN-CODE               
                   END-IF                                               
               END-IF                                                   
               ADD  1                  TO TALLY                         
           END-PERFORM.                                                 
      *                                                                 
           INSPECT LS-DISPLAY-X        CONVERTING 'ABCDEF'             
                                       TO X'FAFBFCFDFEFF'.             
      *                                                                 
           MOVE LS-DISPLAY-V9          TO LS-PACKED-V9.                 
           MOVE LS-RETURN-CODE         TO RETURN-CODE.                 
      *                                                                 
           GOBACK.
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