Aimed at the experienced RPG programmer, this book will quickly take you from your RPG III skills to writing powerful RPG IV programs. It addresses the difference between RPG III and RPG IV so that you can quickly become a productive RPG IV programmer. This book contains extensive code examples that compare the two RPG languages and also introduces the ILE capabilities that can be used to your advantage. There are two new chapters on subprocedures: one that explains why the powerful new capabilities of subprocedures that let you break modules down into multiple procedures are so important, and another that shows you, by example, how to code the P-specs that make it all possible. They have added a chapter on conditional compiler objects to show you how the old directives have been enhanced, and what new directives are available. And finally, they have added a chapter on implementing object-oriented concepts in RPG. With the industry quickly moving towards OO programming, it is critical that RPG programmers keep up to date on this powerful concept and understand how it applies to modern RPG IV constructs. There are also appendixes with utilities and programs that you can add to your copy book and learn from: changing case with RPG IV subprocedures, converting numbers to words, recursive programming, and exception and error codes, plus another new appendix with the limit changes for RPG IV defined. (Level: Intermediate to Advanced).