IBM RPG (Report Program Generator) is a high-level programming language that has been used to create business applications since the mid-1960s. Originally designed for punch card processing, it has since evolved to support modern platforms such as IBM i. In this guide, we will provide an overview of the history of IBM RPG, its syntax and structure, and the best applications for it. We will also provide a simple example to help you get started with writing RPG programs.
History of IBM RPG
IBM RPG was created by IBM in the early 1960s as a language for developing business applications for punch card machines. It was originally called RPG II and was designed to simplify the process of generating reports from data stored on punch cards. Over time, the language evolved to support new technologies such as magnetic tape and disk storage.
In the 1980s, IBM introduced the System/38, which included a new version of RPG called RPG III. RPG III was a significant improvement over earlier versions of the language, with support for structured programming and the ability to work with external databases.
In the 1990s, IBM introduced the AS/400, which included a new version of RPG called RPG IV. RPG IV was a major overhaul of the language, with support for object-oriented programming, modular code, and integration with other programming languages such as Java.
Syntax and Structure of IBM RPG
IBM RPG has a fixed-format syntax, which means that each line of code must start in a specific column. Here is an example of a simple RPG program:
01. H Mainframe News Demo Program
02. FNewsdemo IF E K DISK
03. C READ Newsdemo
04. C IF %EOF(Newsdemo)
05. C LEAVE
06. C ENDIF
07. C EXSR ProcessNews
08. C ENDDO
09. C SETON LR
10. P ProcessNews B
11. C EVAL NewsSum = NewsSum + NewsAmt
12. C RETURN
In RPG, the program is divided into fixed-format sections, including a header section (lines 1-2), a main processing section (lines 3-8), and a subprocedure section (lines 10-12). Each line of code starts in a specific column, with the first six columns reserved for line numbers and other indicators.
Best Applications for IBM RPG
IBM RPG is well-suited for developing business applications, particularly those that involve data processing and report generation. It is commonly used in industries such as manufacturing, finance, and healthcare.
One of the strengths of RPG is its integration with IBM i, which allows it to work seamlessly with other IBM technologies such as DB2 databases and RPG's own database system, DDS.
Example Program
Here is a simple RPG program that reads data from a database file and generates a report:
01. H My Report Program
02. FMyFile IF E K DISK
03. C SETON LR
04. C EXFMT Header
05. C WRITE Detail
06. C READ MyFile
07. C DOW NOT %EOF(MyFile)
08. C WRITE Detail
09. C READ MyFile
10. C ENDDO
11. C
In this example, the program reads data from a database file called MyFile (line 2) and generates a report with a header (line 4) and detail lines (lines 5-10). The program uses a loop (lines 7-10) to read through all the records in the file and generate a report line for each record.
Conclusion
IBM RPG is a high-level programming language that has been used for decades to develop business applications. It has evolved over time to support modern platforms such as IBM i and is particularly well-suited for data processing and report generation. In this guide, we have provided an overview of the history of IBM RPG, its syntax and structure, and the best applications for it. We have also provided a simple example to help you get started with writing RPG programs. With this guide, you should be well-equipped to start exploring IBM RPG and leveraging its power for your own business applications.