ILE RPG programm won't compile

Question

I'm quite new in ILE RPG. Today I started to work out book from my work. In one of the chapter there are some samples of the usage of the Substring function %SUBSTR. Here is the code:

DMOD              S              5    INZ('VWXYZ')                     
DCON              S              5    INZ('abcde')                     
DLENGTH           S              5  0 INZ(2)                           
DSTART1           S              5  0 INZ(3)                           
DSTART2           S              5  0 INZ(4)                           
D*                                                                     
C     mod           DSPLY                                              
C     con           DSPLY                                              
C     start1        DSPLY                                              
C     start2        DSPLY                                              
C     length        DSPLY                                              
C*                                                                     
C                   EVAL      %SUBST(mod:3:2) = con                    
C*                                                                     
C                   EVAL      %SUBST(mod : 3 : 2) = %SUBST(con : 4 : 2)
C*                                                                     
C                   EVAL      %SUBST(mod:start1:length) =              
C                             %SUBST(con:start1:length)                
C*                                                                     
C                   EVAL      %SUBST(mod:start1-1:length) =            
C                             %SUBST(con:start2/2:length+1)            
C*                                                                     
C                   MOVE      *ON           *INLR 

When compiling, there is a abnormal execution that tells me there is wrong parameter in function %SUBST. To be exact: the second parameter is wrong. I only get this error in the last EVAL.

Answer 1

You're running afoul of RPG's precision rules...

The / operator is not integer division, it's numeric and the results have a decimal place.

You'll need to explicitly control the result type of your expression:

DMOD              S              5    INZ('VWXYZ')                          
DCON              S              5    INZ('abcde')                          
DLENGTH           S              5  0 INZ(2)                                
DSTART1           S              5  0 INZ(3)                                
DSTART2           S              5  0 INZ(4)                                
D*                                                                          
C     mod           DSPLY                                                   
C     con           DSPLY                                                   
C     start1        DSPLY                                                   
C     start2        DSPLY                                                   
C     length        DSPLY                                                   
C*                                                                          
C                   EVAL      %SUBST(mod:3:2) = con                         
C*                                                                          
C                   EVAL      %SUBST(mod : 3 : 2) = %SUBST(con : 4 : 2)     
C*                                                                          
C                   EVAL      %SUBST(mod:start1:length) =                   
C                             %SUBST(con:start1:length)                     
C*                                                                          
C                   EVAL      %SUBST(mod:start1-1:length) =                 
C                             %SUBST(con:%int(start2 / 2):length+1)         
C*                                                                          
C                   MOVE      *ON           *INLR