Variables for writing CLP AS400 programming begin with the sign ‘&’ and doeclare at the beginning of the program. Variables have 6 types including: Decimal (*DEC), Character (*CHAR), Logical (*LGL), Integer (*INT), Unsigned Integer (*UINT) and Pointer (*PTR).

For example, I will make a variable with type *CHAR. The CHGVAR command is used to change the value variable.

PGM                                                                  
/* DECLARE VARIABLE VAR1 WITH TYPE CHAR, LENGTH 100 AND INIT VALUE */
             DCL        VAR(&VAR1) TYPE(*CHAR) LEN(100) +            
                          VALUE('Intial Value')                      
                                                                     
/* SEND PROGRAM MSG VALUE VAR1 */                                    
             SNDPGMMSG  MSG(&VAR1)                                   
                                                                     
/* CHANGE VALUE VAR1 */                                              
             CHGVAR     VAR(&VAR1) VALUE('Hello World!')             
                                                                     
/* SEND PROGRAM MSG NEW VALUE VAR1 */                                
             SNDPGMMSG  MSG(&VAR1)                                   
                                                                     
ENDPGM                                                               

Compile and run the program: