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Learn Rpg - 10 Code Examples & CST Typing Practice Test

RPG (Report Program Generator) is a high-level programming language primarily used for business applications, especially on IBM midrange systems like AS/400 and IBM i, for generating reports and handling data processing tasks.

View all 10 Rpg code examples →
RPG Counter and Theme ToggleRPG Fibonacci SequenceRPG Factorial CalculatorRPG Prime CheckerRPG Sum of ArrayRPG Reverse StringRPG Multiplication TableRPG Temperature ConverterRPG Simple Alarm SimulationRPG Random Walk Simulation

Learn RPG with Real Code Examples

Updated Nov 20, 2025

Explain

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.

Core Features

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

Basic Concepts Overview

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

Project Structure

src/ - RPG source files

lib/ - reusable subprocedures

reports/ - generated output files

tests/ - sample input/output files

docs/ - business rules and program documentation

Building Workflow

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

Difficulty Use Cases

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

Comparisons

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

Versioning Timeline

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

Glossary

F-spec: file definition

D-spec: data definition

C-spec: calculation spec

RPG IV: modern free-format RPG

Subprocedure: modular reusable code

Installation Setup

Install IBM i (AS/400) system or emulator

Set up development environment (RDi or SEU)

Configure DB2 files for input/output

Test simple calculation/report programs

Verify IBM i environment paths and libraries

Environment Setup

Install IBM i or emulator

Set up development IDE (RDi or SEU)

Configure DB2 database files

Create libraries for source and output

Compile and test programs

Config Files

RPG source files (.RPG, .rpgle)

DB2 table definitions

Library paths for IBM i

Batch job configurations

Report layout specifications

Cli Commands

CRTRPGMOD - create RPG module

CRTBNDRPG - compile RPG program

CALL programName - run program

WRKJOB - monitor job execution

DSPPGM - display program info

Internationalization

Used globally in enterprises running IBM i

Supports multiple languages in business data

Date and numeric formats configurable

Reports adaptable to local standards

Documentation available in multiple languages

Accessibility

Stable and well-documented in IBM i ecosystem

Training and tutorials available for legacy systems

Accessible through RDi IDE and emulators

Strong backward compatibility

Interactive and batch execution modes

Ui Styling

Text-based interactive screens

Report outputs formatted for printing

Optional GUI via modern APIs

Console and terminal-based execution

Legacy green-screen style terminals

State Management

Variables store program data

Files maintain persistent records

Subprocedures modularize logic

DB2 tables provide structured data storage

Program flow managed by procedural sequence

Data Management

Files (input/output) and records

Variables (numeric, character, date)

Arrays in modern RPG IV

DB2 tables and queries

Temporary storage for calculations

Architecture

Procedural language focused on file and record operations

Batch and interactive execution supported

Integration with DB2 database for data access

Modular subprocedures for reuse

Report-oriented I/O for business applications

Rendering Model

Source code compiled by IBM i compiler

Program executes record by record

Calculations and logic applied to each record

Reports formatted for output files

Optional interactive display for user input

Architectural Patterns

Procedural and modular subprocedure-based design

File I/O driven workflow

Batch processing and scheduling

Integration with DB2 database

Report-centric application structure

Real World Architectures

Payroll processing systems

Inventory management systems

Financial reporting applications

Customer billing and order processing

ERP modules on IBM i

Design Principles

Optimized for business reports and calculations

File-centric and record-oriented

Procedural with optional modularization

Batch and interactive execution support

Integration with DB2 and IBM i features

Scalability Guide

Modularize large programs into subprocedures

Organize libraries for reusable code

Optimize batch job performance

Use indexes for DB2 queries

Implement error handling and logging

Migration Guide

Transition fixed-format RPG to free-format RPG IV

Refactor calculations into subprocedures

Update file access for modern DB2 tables

Leverage APIs for GUI or web integration

Maintain backward compatibility for legacy jobs

Performance Notes

Optimized for batch processing

Efficient file-based calculations

Leverage built-in DB2 integration for speed

Avoid unnecessary nested loops

Use modular subprocedures to improve maintainability

Security Notes

RPG programs follow IBM i security settings

Ensure proper file permissions

Control user access to sensitive data

Secure batch job submissions

Audit critical calculations

Monitoring Analytics

Monitor job execution on IBM i

Check report outputs for correctness

Validate calculations with sample data

Review DB2 query performance

Audit logs for critical business processes

Code Quality

Consistent variable and file naming

Clear modularization with subprocedures

Proper error handling

Readable calculation and report logic

Comment legacy and modern RPG code

Practical Examples

Monthly sales report generator

Payroll calculation program

Inventory tracking and reorder alerts

Customer billing and invoicing

Financial statement preparation

Troubleshooting

Check file definitions and library paths

Verify calculation and format specifications

Ensure subprocedures are compiled

Debug record I/O errors

Check DB2 integration for correct queries

Testing Guide

Verify file I/O correctness

Test calculations with sample data

Check report formatting

Validate subprocedure execution

Compare outputs with expected results

Deployment Options

IBM i batch jobs

Interactive terminal programs

Integrated ERP modules

Web services using RPG backend

Legacy system maintenance and migration

Tools Ecosystem

IBM Rational Developer for i (RDi)

Source Entry Utility (SEU)

DB2 for IBM i

IBM i Navigator

Emulators for testing (e.g., MBAS, TN5250)

Integrations

DB2 relational database

Interactive CL programs

Batch job scheduling on IBM i

Web and GUI interfaces via APIs

ERP and legacy business systems

Productivity Tips

Use subprocedures for modular design

Leverage free-format RPG for readability

Test small units before integrating

Document calculations and report layouts

Automate batch jobs for efficiency

Challenges

Generate a monthly sales report

Build payroll processing program

Develop inventory tracking system

Create customer billing module

Maintain legacy IBM i applications

Learning Path

Start with fixed-format RPG IV

Learn file handling and record operations

Practice calculations and report formatting

Explore subprocedures and modular design

Integrate DB2 database operations

Skill Improvement Plan

Week 1: Basic RPG syntax and reports

Week 2: File I/O and calculations

Week 3: Subprocedures and modular coding

Week 4: DB2 integration and batch jobs

Interview Questions

What is RPG used for?

Difference between fixed and free-format RPG?

Explain RPG file I/O operations

How are subprocedures used in RPG?

How does RPG integrate with DB2?

Cheat Sheet

F-spec: file definitions

D-spec: data/variable definitions

C-spec: calculations

P-spec: procedures

RPG IV free-format: calculation statements in source lines

Books

RPG IV Programming on IBM i

Mastering RPG IV

RPG IV for Experienced Programmers

RPG IV by Example

Practical RPG IV Programming

Tutorials

Getting Started with RPG IV

File I/O in RPG

Subprocedures and Modular Design

Report Generation Examples

Legacy RPG Maintenance Techniques

Official Docs

IBM Knowledge Center: RPG Reference

IBM i RPG IV Programming Guide

IBM RPG manuals and technical notes

Community Links

IBM i developer forums

Reddit r/IBMi

LinkedIn RPG groups

Midrange Systems community

GitHub repositories for RPG examples

Community Support

IBM i developer forums

Midrange systems user groups

Reddit r/IBMi

LinkedIn RPG developer groups

IBM Knowledge Center resources

Monetization

Legacy enterprise system maintenance

IBM i development consulting

ERP module enhancement

Financial system modernization

Training and documentation services

Future Roadmap

Continued support on IBM i platforms

Integration with modern web and APIs

Free-format RPG adoption

Legacy system modernization projects

Ongoing enterprise maintenance and consulting

When Not To Use

Modern web or mobile app development

Non-IBM legacy system projects

High-performance computing outside IBM i

Rapid prototyping or startups

Open-source or cross-platform software

Final Summary

RPG is a legacy programming language specialized for business data processing.

Strongly integrated with IBM i systems for batch and interactive applications.

Still relevant in finance, manufacturing, and logistics enterprises.

Modern free-format RPG improves readability and maintainability.

Faq

Is RPG still used?

Yes - mainly in IBM i/AS400 legacy systems.

Can RPG handle modern applications?

Yes, via free-format RPG and integration with APIs.

Is RPG only for reports?

Originally yes, but modern RPG handles business logic too.

Why learn RPG today?

Legacy enterprise systems still require maintenance and modernization.

Code Sample Descriptions

1

RPG Counter and Theme Toggle

D COUNT           S              5I 0 INZ(0)
D ISDARK          S              1A   INZ('0')

C     *ENTRY    PLIST
C               PARM                    

C     UPDATEUI  BEGSR
C               WRITE 'Counter:' COUNT
C               IF ISDARK = '1'
C                 WRITE 'Theme: Dark'
C               ELSE
C                 WRITE 'Theme: Light'
C               ENDIF
C               ENDSR

C     INCREMENT  BEGSR
C               COUNT += 1
C               PERFORM UPDATEUI
C               ENDSR

C     DECREMENT  BEGSR
C               COUNT -= 1
C               PERFORM UPDATEUI
C               ENDSR

C     RESET      BEGSR
C               COUNT = 0
C               PERFORM UPDATEUI
C               ENDSR

C     TOGGLETHEME BEGSR
C               IF ISDARK = '0'
C                 ISDARK = '1'
C               ELSE
C                 ISDARK = '0'
C               ENDIF
C               PERFORM UPDATEUI
C               ENDSR

C     *MAIN      BEGSR
C               PERFORM UPDATEUI
C               PERFORM INCREMENT
C               PERFORM INCREMENT
C               PERFORM TOGGLETHEME
C               PERFORM DECREMENT
C               PERFORM RESET
C               ENDSR

Demonstrates a simple counter with theme toggling using RPG variables and WRITE statements.

Let’s Try →
2

RPG Fibonacci Sequence

D A               S              5I 0 INZ(0)
D B               S              5I 0 INZ(1)
D C               S              5I 0
D I               S              5I 0

C     *ENTRY    PLIST
C               PARM
C               WRITE A
C               WRITE B
C               FOR I = 1 TO 8
C                 C = A + B
C                 WRITE C
C                 A = B
C                 B = C
C               ENDFOR

Generates the first 10 Fibonacci numbers.

Let’s Try →
3

RPG Factorial Calculator

D N               S              5I 0 INZ(5)
D F               S              10I 0 INZ(1)
D I               S              5I 0

C     *ENTRY    PLIST
C               PARM
C               FOR I = 1 TO N
C                 F = F * I
C               ENDFOR
C               WRITE F

Calculates factorial of a number.

Let’s Try →
4

RPG Prime Checker

D N               S              5I 0 INZ(13)
D ISPRIME         S              1A  INZ('Y')
D I               S              5I 0

C     *ENTRY    PLIST
C               PARM
C               FOR I = 2 TO N-1
C                 IF N MOD I = 0
C                   ISPRIME = 'N'
C                   LEAVE
C                 ENDIF
C               ENDFOR
C               IF ISPRIME = 'Y'
C                 WRITE 'Prime'
C               ELSE
C                 WRITE 'Not Prime'
C               ENDIF

Checks if a number is prime.

Let’s Try →
5

RPG Sum of Array

D ARR             S              5I 0 DIM(5) INZ(1:2:3:4:5)
D SUM             S              10I 0 INZ(0)
D I               S              5I 0

C     *ENTRY    PLIST
C               PARM
C               FOR I = 1 TO 5
C                 SUM += ARR(I)
C               ENDFOR
C               WRITE SUM

Calculates the sum of an array.

Let’s Try →
6

RPG Reverse String

D STR             S              20A  INZ('HELLO')
D REV             S              20A  INZ('')
D I               S              5I 0

C     *ENTRY    PLIST
C               PARM
C               FOR I = %LEN(STR) TO 1 BY -1
C                 REV = REV + %SUBST(STR:I:1)
C               ENDFOR
C               WRITE REV

Reverses a string.

Let’s Try →
7

RPG Multiplication Table

D N               S              5I 0 INZ(5)
D I               S              5I 0

C     *ENTRY    PLIST
C               PARM
C               FOR I = 1 TO 10
C                 WRITE N:' x ':I:' = ':N*I
C               ENDFOR

Prints multiplication table of a number.

Let’s Try →
8

RPG Temperature Converter

D C               S              10I 0 INZ(25)
D F               S              10I 0

C     *ENTRY    PLIST
C               PARM
C               F = (C * 9 / 5) + 32
C               WRITE F

Converts Celsius to Fahrenheit.

Let’s Try →
9

RPG Simple Alarm Simulation

D TEMP            S              5I 0 INZ(80)
D THRESH          S              5I 0 INZ(75)

C     *ENTRY    PLIST
C               PARM
C               IF TEMP > THRESH
C                 WRITE 'Alarm: Temperature Too High!'
C               ELSE
C                 WRITE 'Temperature Normal'
C               ENDIF

Simulates an alarm when temperature exceeds threshold.

Let’s Try →
10

RPG Random Walk Simulation

D STEPS           S              5I 0 INZ(10)
D POS             S              5I 0 INZ(0)
D I               S              5I 0

C     *ENTRY    PLIST
C               PARM
C               FOR I = 1 TO STEPS
C                 IF %RAND < 0.5
C                   POS += 1
C                 ELSE
C                   POS -= 1
C                 ENDIF
C                 WRITE POS
C               ENDFOR

Simulates a 1D random walk.

Let’s Try →

Frequently Asked Questions about Rpg

What is Rpg?

RPG (Report Program Generator) is a high-level programming language primarily used for business applications, especially on IBM midrange systems like AS/400 and IBM i, for generating reports and handling data processing tasks.

What are the primary use cases for Rpg?

Generating business reports. Batch data processing. Financial calculations. Inventory and logistics management. Legacy enterprise application maintenance

What are the strengths of Rpg?

Highly optimized for business data processing. Legacy systems are stable and reliable. Deep integration with IBM i/AS400. Efficient for batch report generation. Strong backward compatibility

What are the limitations of Rpg?

Steep learning curve for modern programmers. Legacy syntax can be cumbersome (fixed format). Limited use outside IBM i ecosystem. Modern web and GUI support is limited. Difficult to integrate with non-IBM systems

How can I practice Rpg typing speed?

CodeSpeedTest offers 10+ real Rpg code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.

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