Here is the ultimate guide to writing RPG IV programs with functions in the free-format style. Let RPG expert and best-selling author Jim Martin show you the way. Want to generate a random number, manipulate a character string, or determine the number of elements in a data structure? There's a function for that. Jim will even show you how to write your own custom built-in functions (BIFs). In this book, you'll discover the role of functions in free-format RPG IV. Jim explains the details of built-in functions (BIFs) and explores the use of C language functions, do-it-yourself functions (subprocedures), and prototyping and procedure interfaces for function connectivity of RPG IV main procedures with subprocedures and other modules. Because functions rely heavily on ILE, the book examines those ILE concepts that connect the parts of a multi-functional program, such as binding, import/export of data, service programs, and binding directories. In addition, you'll find how to prototype IBM's APIs.