Learn RPG with Real Code Examples

RPG was designed for business data processing and report generation.

It emphasizes record-level file operations, calculations, and output formatting.

Still used in legacy enterprise systems, particularly in finance, manufacturing, and logistics.

File I/O operations with input/output files

Calculations and data manipulation

Report formatting (line and column-based)

Subprocedures and modularization

Integrated with DB2 on IBM i systems

Fixed-format vs free-format RPG IV

Files (input/output) and record structures

Calculation specifications (C-specs)

Report formatting (R-specs)

Subprocedures and modular code

src/ - RPG source files

lib/ - reusable subprocedures

reports/ - generated output files

tests/ - sample input/output files

docs/ - business rules and program documentation

Write source code in RPG (fixed or free format)

Compile using IBM i compiler

Run programs on IBM i or emulator

Test file I/O and calculations

Generate business reports or batch outputs

Beginner: simple calculations and report generation

Intermediate: batch data processing and DB2 integration

Advanced: interactive IBM i applications

Expert: large enterprise system maintenance

Legacy migration or integration projects

More specialized than COBOL for report generation

Less versatile than modern languages

Tightly coupled with IBM i ecosystem

Stable and mature for enterprise applications

Legacy syntax differs from modern procedural languages

1959 – RPG created by IBM for IBM 1401

1960s – RPG II for IBM System/3

1978 – RPG III for IBM System/38

1994 – RPG IV introduced with free-format syntax

2000s+ – Ongoing updates for IBM i compatibility

F-spec: file definition

D-spec: data definition

C-spec: calculation spec

RPG IV: modern free-format RPG

Subprocedure: modular reusable code