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RPG IV Introduction


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Over the years, the RPG programming language has evolved from strictly a reporting tool (not too different in scope from today's Query/400) to a robust, full-featured language.  In version 3, release 1 (V3R1) IBM introduced a new version of RPG named ILE RPG for AS/400.  This release was perhaps the most significant since the original inception of the language.

There is often a great deal of confusion about the naming convention of the RPG versions.  The terms RPG ILE and RPG IV are often used interchangeably, and in truth, they are the same product.  However, there is a difference between RPG IV and RPG ILE.  The way I like to explain this is that RPG IV is simply the next version of RPG.  After this will be RPG V.  RPG IV has a whole host of improvements over RPG III (also known as RPG/400) many of which we'll be covering later on.

ILE on the other hand is a set of functionality that exists across multiple programming languages (C, CL, Cobol).  ILE stands for Integrated Language Environment.  It gets it's name from the ability to create a single program using multiple programming languages.  Therefore, RPG IV is ILE compliant.  Calling the language RPG ILE is not really sufficient, as when RPG V is released, it will be ILE compliant as well.  Throughout this document however, the terms RPG IV and RPG ILE may be used interchangeably.

The ILE functionality of RPG IV provides a vast number of functional, performance, maintenance, and productivity benefits to the RPG programmer (not just the ability to integrate multiple languages).  We've included an ILE primer to give a brief overview of the concepts and benefits of ILE.  However, the enhancements can be a bit overwhelming, especially if you have no experience with object oriented programming languages such as Java or C++.  Although not truly object oriented, ILE does provide many of the benefits of object-oriented languages.

Therefore, it is recommended that an RPG III programmer begin exploration of RPG IV with the non-ILE specific language elements.  As you begin to get comfortable with the new features and layouts, then explore the benefits of ILE.

Putting ILE functionality aside for the moment, RPG IV has a number of enhancements from RPG III that justify making the switch.

  • Longer field names
  • Source level debugging
  • Date and time support
  • Additional data types (floating point, boolean, pointers)
  • Free-format expressions
  • Built in functions
  • Case tolerance

The quickest and easiest way to get started with RPG IV is to convert an existing RPG III program and explore that.

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Last Modified:  December 15, 2000