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TechTip: Make Comments in RPG Stand Out

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Many iSeries programmers do a great job of writing comments within their RPG IV code, and as far as I am concerned, the more comments the better. I once saw code with comments that jumped right out at me because the comments were white, with the code green. The programmer had "borrowed" the program that had this in it from someone else, who borrowed from another, etc. It sounded like borrowing yeast for bread as our ancestors once did.

I also borrowed one of these programs, populating my comments to white as well. Finally, my curiosity overcame me, and I decided to check out how this little trick was done. Just before the comment, in the same line, was what appeared to be a blank, but upon further investigation, it was not a blank at all. It was a value of hex 22. I found this out by doing a display of the physical file member for my program source. When the source line is sent to the screen, using SEU, the hex 22 changes the display attribute of the remainder of the line to high intensity. Since I am using a 5250 emulator (Client Access), high intensity doesn't exist, so the emulator sets the color to white.

The following is a short RPG IV program that you can use to set your comments to appear in white, regardless of whether you prefer fixed-format or free-format calculations. You must use V5R1 (or later) to compile the program. I have called the program SRCCMTHI (for source comments high intensity):

 * Program SRCCMTHI to turn comments to white within an RPGLE source member
 * The source member to be affected is determined by an Ovrdbf command
 *   Example:   OVRDBF FILE(QRPGLESRC) MBR(source-program-name)
 *              CALL SRCCMTHI
F Qrpglesrc  UF   e              disk        Rename(Qrpglesrc:Rec)
 * Constants and variables
D Hex22    C                      X'22'
D loc    S            2  0
D fflag                S             n
 
 * Data structure to help minimize substringing
D                      DS
D Srcdta
D Stdcomment   2 overlay(Srcdta:7)
D free   5 overlay(Srcdta:7)
D Calcmt  69 overlay(Srcdta:8)

 /free
  Read Rec; // Read first source statement
  Dow not %eof;                         // While not at eof
    If Stdcomment = '* ';               // Position 7 is * and 8 a blank?
      %subst(srcdta:8:1) = Hex22;       //   Yes – put the high int. char in 8
    Elseif  free = '/free'              //   No – Is this free-format start?
        or  free = '/Free'              //     (differing upper/lower case)
        or  free = '/FREE';
      fflaf = *On;                      //     Yes, set free-format flag
    Elseif  fflag = *On;                //   Is fflag set from earlier time?
      If    free = '/end-'              //     Is this an end-free line?
         or free = '/End-'              //      (differing upper/lower case)
         or free = '/END-';
        fflag = *Off;                   //       Yes, reset free format flag
      Else;                             //       No
        Loc = %scan('//':Calcmt:1);     // Find start of free format comment
        If loc > 0 and %subst(Calcmt:loc+2:1) = *blank // Found comment and
       // next char after slashes is a blank
          %subst(Calcmt:Loc+2:1) = Hex22; // Set high int. byte after slashes
        Endif;
      Endif;
    Endif;
    Update Rec;                         // Update every record
    Read Rec;                           // Read next record
  Enddo;
  *Inlr = *On;                          // End program
 /end-free

This code will work if there are compile time arrays or tables, unless there is an asterisk (*) in position 7 followed by a space in 8 within the table/array data. If that happens, the space is turned into a hex 22. No results are guaranteed if you use this code, but it has worked well for me so far.

You may want to try the program first with a copy of your source program, just to see if you're going to like the results.

Jim Martin is corporate technical instructor at Jack Henry & Associates in Monett, Missouri. He is a veteran of RPG programming, beginning in 1967 with a position at IBM as a systems engineer and later was a staff programmer at the Rochester systems programming lab. For eight years, he was at Lakeview Technology as an AS/400 and RPG instructor and was a speaker at various local midrange user group meetings and conferences. He can be reached by email at This email address is being protected from spambots. You need JavaScript enabled to view it..


JIM MARTIN

Jim Martin holds a BS degree in mathematics and an MS in computer science. For 26 years, he was employed by IBM, where he wrote RPG applications for customers and worked in the programming laboratory as a programmer on portions of CPF and the OS/400 operating system. After leaving IBM, Jim took post-graduate work in computer science and performed RPG training. He is an IBM-certified RPG IV developer and author of multiple bestselling editions of Free-Format RPG IV, which, since the book's initial publication in 2005, have taught thousands of RPG IV programmers how to be successful with the free-format coding style.

MC Press books written by Jim Martin available now on the MC Press Bookstore.

Free-Format RPG IV: Third Edition Free-Format RPG IV: Third Edition
Improve productivity, readability, and program maintenance with the free-format style of programming in RPG IV.
List Price $59.95

Now On Sale

Free-Format RPG IV: Second Edition Free-Format RPG IV: Second Edition
>Make the transition from coding in fixed-format RPG to free format.
List Price $59.95

Now On Sale
Functions in Free-Format RPG IV Functions in Free-Format RPG IV
Here’s the ultimate guide to writing RPG IV programs with functions in the free-format style.
List Price $59.95

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