OS/2 Procedures Language 2/REXX


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Writing a REXX Procedure


We shall write the following REXX procedure using a text editor. To write 
a REXX procedure named HELLO.CMD while using the text editor follow these 
instructions: 
   1. Create a text file named HELLO.CMD. 
   2. Type the procedure HELLO.CMD, as follows: 

      /* An introduction to REXX */
      SAY "Hello! I am REXX"
      SAY "What is your name?"
      PULL who
       IF who = ""
        THEN
        SAY "Hello Stranger"
       ELSE
        SAY "Hello" who
      EXIT
      
      
   3. Save the file and exit from the text editor. 
 
 Now you are ready to run the REXX procedure you have written.  Type the 
 name of the procedure at the OS/2 command prompt and press Enter. 

 hello
 
 
 When the procedure pauses, you can either type your name or press Enter 
 to see the other response. 
 A brief description of each part of HELLO.CMD follows: 
 /* An introduction to REXX */   A comment explains what the procedure is 
 about.  A comment starts with a /* and ends with a */.  All REXX 
 procedures must start with a comment on line one and column one of the 
 file.  The comment tells the command processor that the procedure being 
 run is a REXX procedure and distinguishes it from simple batch files. 
 SAY "Hello! I am REXX." SAY "What is your name?"   These instructions 
 cause the words between the quotation marks to be displayed on your 
 screen. 
 PULL who   The PULL instruction reads the response entered from the 
 keyboard and puts it into the system's memory.  Who is the name of the 
 place in memory where the user's response is put.  Any name can be used 
 with the PULL instruction. 
 IF who = " "   The IF instruction tests a condition.  The test in this 
 example determines if who is empty.  It is empty if the user types a 
 space and presses Enter or just presses Enter. 
 THEN   Specifies that the instruction that follows is to be run, if the 
 tested condition is true. 
 SAY "Hello Stranger"   Displays Hello Stranger on the screen. 
 ELSE   Specifies that the instruction that follows is to be run if the 
 tested condition is not true. 
 SAY "Hello" who   Displays Hello on the screen, followed by whatever is 
 in who. 
 EXIT   This instruction causes the procedure to stop. 
 Here is what would happen if a person named Bill tried the HELLO program: 
 

 [C:\]hello
 Hello! I am REXX.
 What is your name?
 
 Bill
 
 Hello BILL
 
 [C:\]
 
 If Bill does not type his name, but types a blank space, this happens: 

 [C:\]hello
 Hello! I am REXX.
 What is your name?
 
 Hello Stranger
 
 [C:\]
 
   

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