You should be beginning to sense that RPG III is powerful but ugly.
Let's recreate this program using the easier to read syntax of RPG IV. The simplest way to do this is to copy TUTR003 in the QRPGLESRC source object and then modify the copied program.
Use PDM to copy TUTR003. Start PDM (STRPDM). You should see something like:
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AS/400 Programming Development Manager (PDM)
Select one of the following:
1. Work with libraries
2. Work with objects
3. Work with members
4. Work with projects
5. Work with groups
6. Work with parts
9. Work with user-defined options
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Key in 3 and hit ENTER. Fill in the screen to look like:
Specify Members to Work With
Type choices, press Enter.
File . . . . . . . . . . QRPGLESRC Name, F4 for list
Library . . . . . . . . user999 *LIBL, *CURLIB, name
Member:
Name . . . . . . . . . *ALL *ALL, name, *generic*
Type . . . . . . . . . *ALL *ALL, type, *generic*,
Of course, change the USER999 to your user ID. Hit ENTER now.Your screen should look like:
Work with Members Using PDM
File . . . . . . QRPGLESRC
Library . . . . USER999 Position to . . . . .
Type options, press Enter.
2=Edit 3=Copy 4=Delete 5=Display 6=Print 7=Rename
8=Display description 9=Save 13=Change text 14=Compile 15=Create
Opt Member Type Text
TUTR002 RPGLE Change the first record in CUST file
TUTR003 RPGLE TUTR002 modified to modern style
Key a 3 as the option next to TUTR003. Hit ENTER and then fill in the screen to copy the program and name it TUTR005:
Copy Members
From file . . . . . . . : QRPGLESRC
From library . . . . : USER999
Type the file name and library name to receive the copied members
To file . . . . . . . . QRPGLESRC Name, F4 for list
To library . . . . . USER999
To rename copied member, type New Name, press Enter.
Member New Name
TUTR003 TUTR005
Hit ENTER and you should now see the copied program in your list. You may want to change the description of the program so you'll remember which program does what.Key a 2 next to TUTR005 so you can change the source statements to the program.The old syntax on the IF and DO statements is legal. So you can choose between:
C *in90 DOWEQ *off AND C DoW *in90 = *offNot only is the second form more readable, it is more free form. You can put spaces and parentheses in the conditional part of the statement like this:
C DoW (*in90 = *off)This may not look like such a big deal, but compare this old style IF statement:
C *in90 IFEQ *off C STATUS ANDEQ 'D' C STATUS OREQ 'A' C CITY ANDEQ 'ATHENS'with the newer style
C If (In90 = *off) and C ((STATUS = 'D') or (STATUS = 'A')) and C (CITY = 'ATHENS')The newer style is not only more readable but you can actually figure out how the conditions are checked.One of the other big changes in form from RPG III to RPG IV is that the subroutine names can be only 6 characters in RPG III. In RPG IV, the subroutine names can be 14 characters. These longer names make the programs many times easier to follow.
So using this new found knowledge about RPG IV, change the program to look like:
FCUST UF E disk C*--------------------------------------------------------------------- C DoW *in90 = *off C Read CUST 90 C If *in90 = *off C Exsr UpdateCSREC C EndIf C EndDo C C Eval *inlr = *on C Return C*--------------------------------------------------------------------- C UpdateCSREC BegSR C C If CSSTE = 'TN' C Eval CSZIP = 987650000 C Update CSREC C EndIf C C EndSRCompile the program with option 14 and you are done.If you really hate using the indicators - and you probably do - you can use one of the new built in functions to check to see if the last record has been read. That is, you are checking to see if the file is at END OF FILE or EOF.
The Do loop can be written:
C DoW not %eof(CUST) C Read CUST C If not %eof(CUST) C Exsr UpdateCSREC C EndIf C EndDoIn fact, the %EOF function will refer to the last file used by default. So you could write:
C DoW not %eof C Read CUST C If not %eof C Exsr UpdateCSREC C EndIf C EndDoIf you have ever used Visual Basic, the EOF function will look familiar.That's it!
Notes:
RPG 3 : C *in90 DOWEQ *off
RPG4 : C *in90 DOWEQ *off
Or C DoW (*in90 = *off)
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RPG3:
C *in90 IFEQ *off
C STATUS ANDEQ 'D'
C STATUS OREQ 'A'
C CITY ANDEQ 'ATHENS'
RPG4:
C If (In90 = *off) and
C ((STATUS = 'D') or (STATUS = 'A')) and
C (CITY = 'ATHENS')
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subroutine names can be only 6 characters in RPG III. In RPG IV, the subroutine names can be 14 characters. These longer names make the programs many times easier to follow.
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