IBM TSO/E REXX User Manual

Comparison operators can compare numbers or strings and ask questions, such as:
Are the terms equal? (A = B)
Is the first term greater than the second? (A > B)
Is the first term less than the second? (A < B)
For example, if A = 4 andB=3,then the results of the previous comparison
questions are:
(A=B)Does4=3? 0 (False)
(A>B)Is4>3? 1 (True)
(A<B)Is4<3? 0 (False)
The more commonly used comparison operators are as follows:
Operator Meaning
== Strictly Equal
= Equal
\== Not strictly equal
\= Not equal
> Greater than
< Less than
>< Greater than or less than (same as not equal)
>= Greater than or equal to
\< Not less than
<= Less than or equal to
\> Not greater than
Note: The not character, "¬", is synonymous with the backslash ("\"). The two
characters may be used interchangeably according to availability and
personal preference. This book uses the backslash ("\") character.
The Strictly Equal and Equal Operators
When two expressions are strictly equal, everything including the blanks and case
(when the expressions are characters) is exactly the same.
When two expressions are equal, they are resolved to be the same. The following
expressions are all true.
'WORD' = word /* returns 1 */
'word ' \== word /* returns 1 */
'word' == 'word' /* returns 1 */
4e2 \== 400 /* returns 1 */
4e2 \= 100 /* returns 1 */
Using Comparison Expressions
Often a comparison expression is used in IF/THEN/ELSE instructions. The following
example uses an IF/THEN/ELSE instruction to compare two values. For more
information about this instruction, see “IF/THEN/ELSE Instructions” on page 42.
Using Expressions
Chapter 3. Using Variables and Expressions 31

IBM TSO/E REXX Specifications

General

Brand	IBM
Model	TSO/E REXX
Category	Computer Hardware
Language	English

Summary

Part 1. Learning the REXX Language

Chapter 1. Introduction

Explains the REXX programming language, its features, and suitability for various users.

Chapter 2. Writing and Running a REXX Exec

Details the process of writing, running, and understanding REXX execs, including syntax rules and common issues.

Chapter 3. Using Variables and Expressions

Covers REXX variables, expressions, operators, and tracing techniques for data manipulation and calculations.

Chapter 4. Controlling the Flow Within an Exec

Explains how to alter REXX exec execution using conditional, looping, and interrupt instructions.

Chapter 5. Using Functions

Describes REXX functions, including built-in, user-written, and packages, and how to use them.

Chapter 6. Writing Subroutines and Functions

Guides on writing, calling, and passing information to REXX subroutines and functions.

Chapter 7. Manipulating Data

Covers REXX data manipulation using compound variables, stems, and various parsing techniques.

Part 2. Using REXX

Chapter 8. Entering Commands from an Exec

Explains how REXX execs can interact with the operating system by issuing TSO/E and host commands.

Chapter 9. Diagnosing Problems Within an Exec

Details techniques for diagnosing and debugging REXX execs using tracing and special variables.

Chapter 10. Using TSO/E External Functions

Describes TSO/E external functions available for interacting with the system and performing specific tasks.

Chapter 11. Storing Information in the Data Stack

Explains how to use the REXX data stack for temporary storage, passing information, and managing buffers.

Chapter 12. Processing Data and Input/Output Processing

Covers dynamic REXX expression modification and processing data to/from data sets using EXECIO.

Chapter 13. Using REXX in TSO/E and Other MVS Address Spaces

Explains how to run REXX execs in TSO/E and non-TSO/E MVS address spaces and available services.

Part 3. Appendixes

Appendix A. Allocating Data Sets

Guides on creating and allocating data sets, including checklists for ISPF/PDF and ALLOCATE commands.

Appendix B. Specifying Alternate Libraries with the ALTLIB Command

Details using the ALTLIB command to specify and manage alternative libraries for implicit execution.

Appendix C. Comparisons Between CLIST and REXX

Compares REXX and CLIST languages, highlighting similarities and differences in features and capabilities.

Appendix D. Notices

Provides legal notices, warranty disclaimers, copyright, and trademark information.

Bibliography

TSO/E Publications

Lists IBM publications related to TSO/E, including administration, CLISTs, and general information.

Related Publications

Lists IBM publications related to z/OS MVS and ISPF, covering system programming and administration.

Index