RPGLE Program Structure

Learning Objective

By the end of this lesson, you will be able to identify the main parts of a simple, modern free-format RPGLE program: control options, declarations, the main calculation logic, and how the program ends.

Simple Explanation

In the Introduction to RPGLE lesson, you learned what RPGLE is used for and that modern RPGLE is commonly written in a free-format style. This lesson looks at the actual shape of a simple free-format RPGLE program, before going deeper into any one part of it in the lessons that follow.

A simple free-format RPGLE program is generally organized into a few recognizable sections, in this order:

• Control options, using the ctl-opt keyword, which set overall behavior for the program as a whole. Many simple programs use only a small number of control options, or none at all.
• Declarations, which introduce the variables the program will use, covered in depth in the Variables and Data Types in RPGLE lesson.
• Calculations, the executable statements that actually do the program's work: assigning values, making decisions, and repeating steps.
• An end-of-program indicator, traditionally set using *inlr = *on;, which tells IBM i that this program's Last Record indicator is on, signaling that the program is finished and should not be left active waiting for more input.

Here is a small, complete example that puts these pieces together:

**free
ctl-opt dftactgrp(*no);

dcl-s custName char(30);

custName = 'Jordan Lee';
dsply custName;

*inlr = *on;

This program declares one variable, assigns it a value, displays that value using the dsply operation, and then ends. Every part of this small example is expanded on in the lessons that follow.

Why It Matters

Recognizing this overall shape, control options, declarations, calculations, end-of-program, gives you a mental map for reading any simple RPGLE program, even one you have never seen before. Rather than feeling like an unstructured block of code, an RPGLE program becomes a small number of recognizable, ordered sections, each with its own clear purpose.

Practical Example

Imagine a new developer opening an RPGLE program for the first time, one they did not write. Even without understanding every line, they can scan the top of the source for ctl-opt to see overall settings, look further down for dcl-s lines to see what variables exist, and then read the remaining calculations to follow what the program actually does step by step, knowing the program will end wherever *inlr = *on; appears.

This is a simplified, illustrative example rather than a specific real program, but it reflects a genuinely useful, practical way to approach reading unfamiliar RPGLE source.

Common Confusions

"Do I need to use ctl-opt in every RPGLE program?" No. Many simple programs use few or no control options at all. ctl-opt is available when a program needs to set specific behavior, but is not required just to have a working program.

"What does *inlr = *on; actually do?" It sets a special built-in indicator, Last Record (*INLR), to on, signaling to IBM i that the program has finished its work. For the simple, standalone programs covered in this lesson group, this is the traditional, straightforward way to end a program cleanly.

"Does dsply write to a file or a screen?" Neither, in the way covered in earlier Db2 for i lessons. dsply is a simple operation that shows a value directly, commonly used for basic output and debugging in small programs, without needing a file or a designed screen.

Quick Recap

• A simple free-format RPGLE program generally has control options, declarations, calculations, and an end-of-program indicator, in that order.
• ctl-opt sets overall program behavior and is optional for simple programs.
• Declarations introduce variables; calculations are the executable statements that do the program's actual work.
• *inlr = *on; is the traditional way to signal that a simple program has finished.

Try Asking the AI Tutor

Use the AI Tutor to ask follow-up questions about this lesson. For example, try asking:

• "What happens if I forget to set *INLR = *ON at the end of my program?"
• "What are some common ctl-opt settings besides DFTACTGRP?"