RPG Programming

Learn how fixed-size RPGLE arrays use DIM, one-based subscripts, and %ELEM to store and process ordered values safely.

Use RPGLE LEAVE and ITER correctly: exit a loop immediately, skip the rest of the current iteration, and keep loop-control…

Learn how pre-test RPGLE DOW loops evaluate their while-condition before the body runs, why the body can execute zero times,…

Learn how post-test RPGLE DOU loops run their body first, evaluate the until-condition at ENDDO, and guarantee at least one…

Learn how counted RPGLE DO loops initialize an index, repeat a controlled block, advance through an inclusive limit, and avoid…

Learn how RPGLE comparison operators and AND/OR logic build boolean conditions, how precedence and grouping actually work, and how to…

Learn how RPGLE guard clauses and early exits can flatten nested conditions, expose the main path, and make procedure logic…

Learn how RPGLE SELECT, WHEN, OTHER, and ENDSL express readable multi-branch decisions, with ordered evaluation and practical business examples.

Learn how RPGLE IF, ELSEIF, ELSE, and ENDIF choose one-way, two-way, and ordered decision paths through practical business examples.

Learn what RPGLE's default (reference-style) parameter passing, VALUE, and CONST actually do to caller storage, with before/after worked examples and…

Learn the difference between an RPGLE variable, a named constant, and a literal, and how to use DCL-C, character/numeric/typed literals,…

Learn RPGLE data structure basics: declare typed subfields, use QUALIFIED access, reuse layouts with LIKEDS, and read simple nested structures.

Use RPGLE character, decimal, integer, date/time, and indicator types correctly by understanding what each declaration's length and precision mean.

Declare RPGLE variables with DCL-S, and see how scope and storage type - automatic, static, and working storage - control…

Organize fully free-form RPGLE with consistent sections, spacing, indentation, continuations, and comments that make program flow easier to review.

Learn how RPGLE indicators and status flags control legacy program flow, and how to map many patterns to clearer fully…

Learn how legacy RPGLE C-specs express calculations and control flow, then map those responsibilities to clear, fully free-form RPGLE logic.

Beginner guide to traditional RPGLE input and output specifications, their relationship to records and fields, and the modern fully free-form…

Beginner guide to RPGLE compiler directives, the **free directive, ctl-opt, and program-wide control options.

Beginner guide to the major sections of a typical RPGLE program and why each section exists.

Beginner guide to clearer RPGLE names, cleaner ordering, and easier-to-maintain code.

Beginner guide to reading RPGLE source in the right order.

Beginner guide to RPGLE editing tools and the edit, compile, diagnose, run workflow.

Beginner guide to the three RPGLE source styles you will see in IBM i code.

Beginner guide to how RPGLE source becomes a compiled IBM i program object.

Beginner guide to RPGLE terminology on IBM i.

Beginner-friendly RPGLE pillar for IBM i.

Master ILE RPG data structures: dcl-ds syntax, qualified data structures with dot notation, LIKEDS for cloning a structure, template data…

Most IBM i shops still manage source the same way they did in the 1990s — members in source physical…

Every RPG developer eventually writes a program that does something it should not. The calculation is wrong. The loop runs…

Most RPG programs are written to handle the happy path. The file exists, the record is found, the calculation succeeds,…

You already know how to read files with READ and CHAIN. They work. But the moment your query involves a…

Subprocedures let you break logic into reusable blocks inside a single program. Service programs take it further — compile your…

You already write RPG. Free-format does not replace what you know — it removes the straitjacket. No more counting columns,…