Adding Comments in REXX

Comments in REXX can be added using C-style comments. A C-style comment begins with /* and ends with */. Everything in between is considered a comment and is ignored by the compiler. The very first comment you’ll add to your exec: /* REXX */. While this is technically only required when writing a REXX script (or EXEC) on the mainframe (e.g., z/OS), it is still a good best practice. So, why is it required on the mainframe? When you’re using an interpreter like Regina on a system like Windows, for instance, you have a file extension (e.g., .rexx). You don’t have this luxury on the mainframe, so /* REXX */ is how you can identify a REXX script from a CLIST script.

How to add inline comments

This is straightforward. Simply find the line of code you want to document and add a message between the /* */ next to it.

say "Hello, World" /* Display a message */

How to add multi-line comments

With multi-line comments you have a couple options. The first looks like this:

/*
  this is an example
  of a comment which spans
  multiple lines
*/

Since anything between the /* */ is treated as a comment this is an easy way to achieve multi-line comments. However, the second option is my preferred method, and it’s called a flower box.

/*******************************************************************/
/* this is also an example                                         */
/* of a comment which spans                                        */
/* multiple lines                                                  */
/*******************************************************************/

I use the flower box when writing lengthy comments or documenting procedures, like this:

/*******************************************************************/
/* FUNCTION: ADD_JCL_COMMENT                                       */
/* PURPOSE : HANDLES COMMENT CREATION IN JCL                       */
/* RETURN  : NONE                                                  */
/*******************************************************************/

Summary

In this #kilobit, you learned how to use the and single and multi-line comments in REXX. Until next time, may the code be with you.