RPG, short for Report Program Generator, is a high-level programming language primarily designed for business applications, report generation, and data processing on IBM midrange systems such as IBM i (formerly AS/400). It is widely used in enterprise environments for batch processing, interactive applications, and financial or administrative reporting. Developers can access RPG through IBM’s official documentation and development environments via IBM RPG resources and IBM i tools, which provide compilers and editors for Windows, Linux, and IBM system platforms.

RPG exists to provide a language optimized for business computing with structured report generation and data file manipulation. Its design philosophy emphasizes readability, concise coding for repetitive tasks, and integration with database files. By offering built-in support for record handling, calculations, and reporting routines, RPG solves the challenge of efficiently producing structured business reports while maintaining compatibility with enterprise data systems.

RPG: Variables and File Operations

RPG programs commonly manipulate database files and use strongly typed variables for calculations and report output.

FEMPFILE   IF   A E           K DISK
D EmployeeID     S              5I 0
D Name           S             20A
D Salary         S             9P 2

C     *ENTRY    PLIST
C               PARM                    EmployeeID
C               READ      EMPFILE
C               IF        %FOUND
C               EVAL      Salary = Salary * 1.05
C               WRITE     EMPFILE
C               ENDIF
C               SETON                                        LR

Files are declared with F-specs, and variables with D-specs. The READ and WRITE operations manipulate data records directly, similar to file handling in COBOL or database scripts in SQL.

RPG: Calculations and Expressions

RPG supports arithmetic, conditional expressions, and calculation logic to process business data.

C               EVAL      TotalSalary = Salary + Bonus
C               IF        TotalSalary > 75000
C               EVAL      Category = 'High'
C               ELSE
C               EVAL      Category = 'Moderate'
C               ENDIF

Calculations use the EVAL operation, and conditional logic provides decision-making. This approach parallels procedural operations in COBOL and SQL procedural extensions.

RPG: Loops and Iteration

RPG allows looping over records and performing repetitive operations efficiently.

C     READLOOP  READ      EMPFILE
C               DOW       %FOUND
C               EVAL      Salary = Salary * 1.05
C               WRITE     EMPFILE
C               READ      EMPFILE
C               ENDDO

Loops using DOW and record-reading operations support batch processing over datasets. This is similar to iterative processing in COBOL or SQL cursors.

RPG: Subroutines and Modularization

RPG supports subroutines for modular code reuse and procedural abstraction.

C     AddBonus  BEGSR
C               EVAL      Salary = Salary + Bonus
C               ENDSR

Subroutines help encapsulate repeated logic, improving maintainability and readability. This is comparable to functions and procedures in COBOL or PL/I.

RPG: Report Formatting

RPG includes facilities for formatting and printing structured reports directly from data files.

C               WRITE     EMPLOYEE_REPORT
C               SETON                                        LR

Reports are generated by defining output layouts and printing records using simple operations, similar to reporting in COBOL or SQL reporting tools.

Overall, RPG provides a powerful, structured, and business-oriented programming environment. When used alongside COBOL, SQL, and PL/I, it enables developers to manipulate enterprise data efficiently, generate reports, and implement business logic reliably. Its combination of file handling, calculations, loops, subroutines, and report formatting ensures RPG remains a cornerstone for enterprise computing on IBM midrange systems.

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