IBM’s proprietary Report Program Generator (RPG) programming language

The Report Program Generator (or RPG for short) is a high-level programming language serves a wide array of business applications and uses. It is an IBM proprietary programming module and a vast majority of its later versions can only be accessed on IBM i- or OS/400-based systems.

RPG actually has quite a long history. It was developed by the tech giant IBM in 1959 as the Report Program Generator- a tool that was developed to serve as an alternative for the punch card processing system on the IBM 1401. However, it was subsequently updated to the RPG II following the development of the IBM System/3 in the 1960s. It has since evolved into the high-level language equivalent of COBOL and PL/I.

To this day, RPG is still a very popular programming language on the AS400 IBMi operating system. RPG IV (also known as ILE RPG) is the most current version of RPG and it is a tool that provides a highly enabling programming environment for AS400 RPG Programmers.

When RPG was first developed, the major stronghold that it had was known as the program cycle. Every RPG program executes programs within a hypothetical loop. This loop is able to apply the same program to every file on record. At that time, there will be a comparison between each record and every line in the program. Every line has the choice to either act on the record or not, based on whether that line has an indicator turned on or off. The entire idea of level breaks and matching records is one that is unique to the RPG II language.

Ever since System/38 was introduced in 1979, majority of RPG programmers stopped making use of the cycle and rather opted for the controlling program flow which has standard looping constructs. However, IB has also continued to provide backward compatibility for the cycle.