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Negative numbers in line sequential files - are they encoded?

  • May 4, 2020
  • 3 replies
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A
  • Anonymous

I noticed that negative numbers seem to be sort of encoded by Visual COBOL when written to line sequential files. PIC S99 VALUE -2, for instance, is stored in a line sequential file as "0r":

 

Is this by intention? I couldn't find any documentation describing how negative numbers are stored in line sequential files. Until now, I would have believed they were stored like any other literal value (e.g. as "-02").

Just in case, please find a sample project attached, depicting the issue.

Your help is appreciated.

    3 replies

    D

    I noticed that negative numbers seem to be sort of encoded by Visual COBOL when written to line sequential files. PIC S99 VALUE -2, for instance, is stored in a line sequential file as "0r":

     

    Is this by intention? I couldn't find any documentation describing how negative numbers are stored in line sequential files. Until now, I would have believed they were stored like any other literal value (e.g. as "-02").

    Just in case, please find a sample project attached, depicting the issue.

    Your help is appreciated.

    Nothing is specifically encoded in a line sequential file (except that with certain environmental settings non-printable characters may be preceded by an x"00" character).  Otherwise the entire record is written as is, and followed by either x"0d0a" or x"0a" (for Windows/Unix respectively, but this may also be affected by environmental settings).

    There is no analysis of the structure of the record, and no knowledge that a particular area of the record corresponds to a numeric field, so no transformation.  In fact that area may anyway be subject to redefinition as  PIC X(n) or whatever.  The COBOL numeric field in your example can however be defined as:

    01 myNumber PIC S99 SIGN IS LEADING SEPARATE.

    ...which will cause the sign to be stored as a separate byte (and therefore to get written out to the line sequential file as a separate character).  LEADING may be replaced by TRAILING for a trailing sign. 

    A
    • Anonymous
    • May 4, 2020

    Nothing is specifically encoded in a line sequential file (except that with certain environmental settings non-printable characters may be preceded by an x"00" character).  Otherwise the entire record is written as is, and followed by either x"0d0a" or x"0a" (for Windows/Unix respectively, but this may also be affected by environmental settings).

    There is no analysis of the structure of the record, and no knowledge that a particular area of the record corresponds to a numeric field, so no transformation.  In fact that area may anyway be subject to redefinition as  PIC X(n) or whatever.  The COBOL numeric field in your example can however be defined as:

    01 myNumber PIC S99 SIGN IS LEADING SEPARATE.

    ...which will cause the sign to be stored as a separate byte (and therefore to get written out to the line sequential file as a separate character).  LEADING may be replaced by TRAILING for a trailing sign. 

    Thanks a lot, Robert!

    Your answer was very informative and enlightening to me.

    With the aid of your answer I was able to find the corresponding help topics in the documentation, providing even more in-depth information about how negative values are stored in sequential files. For anyone stumbling over this question at a later time, I'd like to list them here for quick reference:

    Claude Greiner
    • Claude Greiner
    • Participating Frequently
    • May 4, 2020

    I noticed that negative numbers seem to be sort of encoded by Visual COBOL when written to line sequential files. PIC S99 VALUE -2, for instance, is stored in a line sequential file as "0r":

     

    Is this by intention? I couldn't find any documentation describing how negative numbers are stored in line sequential files. Until now, I would have believed they were stored like any other literal value (e.g. as "-02").

    Just in case, please find a sample project attached, depicting the issue.

    Your help is appreciated.

    this is ok so in mf-files. by negativ values the last sign is a character, for 02- 0r, etc....

    You can work correctly with this automatically coding!

    you can store sign trealing or leading, when you define this.

    rm directive store the sign leading, when i remember me correctly.

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