Conditional Execution of RPG IV Statements (If-Else)

In RPGLE we have the following conditional opcodes available.
The If-EndIf block.
The If - Else- EndIf block.
The If - ElseIf - Else - EndIf block.
We will learn them one by one.

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The If-EndIf in RPGLE

If we want some RPGLE Statement(s) to be executed conditionaly. We put these statements inside an If-EndIf block. We specify the condition in the factor 2 of the If opcode. The following example will clarify the If-EndIf in ILE RPG.

Simple If Example in RPGLE

DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords
DW@Char           S              1A   Inz('A')
 **                                           
CL0N01Factor1+++++++Opcode&ExtExtended-factor2
C                   If        W@Char = 'A'    
C     W@Char        Dsply          
C                   EndIf                     
 **                                           
C                   Return                    

The output of the above program is as expected 'A'

DSPLY  A

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The If-Else-EndIf in RPGLE

If we want some RPGLE Statement(s) to be executed conditionaly and different set of statement if the condition fails, we use If-Else-EndIf blocks.
The following example will clarify it further.

Simple If-Else Example in RPGLE

DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++
DW@Char           S              1A   Inz('A')               
DW@Msg1           S             20A   Inz('W@Char is A')     
DW@Msg2           S             20A   Inz('W@Char not ''A''')
 **                                                          
CL0N01Factor1+++++++Opcode&ExtExtended-factor2+++++++++++++++
C                   If        W@Char = 'A'                   
C     W@Msg1        Dsply                                    
C                   Else                                     
C     W@Msg2        Dsply                                    
C                   EndIf                                    
 **                                                          
C                   Return                                   

The above program displays the text of W@Msg1. You can try to run the else condition by initializing W@Char with 'B' or some other character.

DSPLY  W@Char is A

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The If-ElseIf-Else-EndIf in RPGLE
If we have multiple sets of condition-statements then we can go for If-ElseIf-Else-EndIf statements. The different conditions are specified as factor 2 of If and ElseIf opcodes. The Else in this condition-rule is optional. Actually, I think the If-ElseIf-Else-EndIf is the only conditional block in RPGLE where Only the first opcode 'If' and its ending opcode 'EndIf' are mandatory! Anyways The following example will illustrate the If-ElseIf-Else-EndIf syntax.

Simple If-ElseIf-Else-EndIf Example in RPGLE

DW@Char           S              1A   Inz('A')          
DW@Msg            S             20A                     
 **                                                     
CL0N01Factor1+++++++Opcode&ExtExtended-factor2++++++++++
C                   If        W@Char = 'B'              
C                   Eval      W@Msg = 'Inside If'       
 **                                                     
C                   ElseIf    W@Char = 'A'              
 **                                                     
C                   Eval      W@Msg = 'Inside ElseIf'   
 **                                                     
C                   Else                                
 **                                                     
C                   Eval      W@Msg = 'Inside Else'     
C                   EndIf                                 
 **                                                  
C     W@Msg         Dsply                            
 **                                                  
C                   Return                          

The above program displays the text of W@Msg at the end of the If-ElseIf-Else-EndIf block. Try to see the display value of message by changing the value of W@Char.

DSPLY  Inside ElseIf

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Nesting in RPGLE
Just like any other language, RPGLE also, allows nesting of several If_ElseIf-Else-EndIf. For all practical purposes, you can rest assured there will not be any problem in streching the nesting into multiple levels. However, using Select-When_EndSl is recommended if the nesting extends more than 3 levels.The follwoing example shows a typical nesting of ILE RPG If-Else.

Example of nested conditions in RPGLE

DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords++++++++++++
DW@Char1          S              1A   Inz('A')            
DW@Char2          S              1A   Inz('B')            
DW@Msg            S             20A                       
 **                                                       
CL0N01Factor1+++++++Opcode&ExtExtended-factor2++++++++++++
C                   If        W@Char1 = 'A'               
 **                                                       
C                   If        W@Char2 = 'B'               
C                   Eval      W@Msg = 'Inside nested if'  
C                   Else                                  
C                   Eval      W@Msg = 'Inside nested Else'
C                   EndIf                                 
 **                                                       
C                   EndIf                                 
 **                                                        
C     W@Msg         Dsply                                  
 **                                                        
C                   Return                                 

The output of the above program is given below. Try to run different conditions of the above program.

DSPLY  Inside nested if