OS/2 Procedures Language 2/REXX


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REXX Features


Some features of REXX that you can use to write more intricate procedures 
will be discussed in this section.  You will see how to have a procedure 
make decisions by testing a value with the IF instruction.  You will also 
see how to compare values and determine if an expression is true or false. 
A brief description of the terms covered in this section follows below: 
 IF                            Used with THEN.  Checks if the expression 
                               is true.  Makes a decision about a single 
                               instruction. 
 THEN                          Identifies the instruction to be run if the 
                               expression is true. 
 ELSE                          Identifies the instruction to be run if the 
                               expression is false. 
 SELECT                        Tells the interpreter to select one of a 
                               number of instructions. 
 WHEN                          Used with SELECT.  Identifies an expression 
                               to be tested. 
 OTHERWISE                     Used with SELECT.  Indicates the 
                               instruction to be run if expressions tested 
                               are false. 
 DO-END                        Indicates that a group of instructions 
                               should be run. 
 NOP                           Indicates that nothing is to happen for one 
                               expression. 
 Comparisons  > <  =           Indicates greater than, less than, equal 
                               to. 
 NOT Operator  ¬ or \          Changes the value of a term from true to 
                               false, or from false to true. 
 AND Operator  &               Gives the value of true if both terms are 
                               true. 
 OR Operator  |                Gives the value of true unless both terms 
                               are false. 
   

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