Presentation © Copyright 2002, Bryan Meyers Introduction to Programming and RPG Chapter 1

Programming in RPG IV Third Edition 2 Objectives Describe the history of RPG Describe program variables Describe the types of data files Describe data hierarchy Explain how data is represented on the printer spacing chart Describe the program development cycle

Programming in RPG IV Third Edition 3 History of RPG Early 1960s: RPG - Report Program Generator Late 1960s: RPG II –With release of System/3 1979: RPG III –Interactive programming –Database –Structured Programming 1988: RPG/400 –Upgrade to RPG III 1994: RPG IV –Integrated Language Environment (ILE) –Modular Programming

Programming in RPG IV Third Edition 4 Program Variables Program variable: a location in the memory of the computer that can store data RPG commonly uses the term field rather than variable All variables used in a program must be defined –Name –Length –Data type

Programming in RPG IV Third Edition 5 Data Files Transaction files –Contain information about day-to-day business occurrences Master files –Contain definitive information about customers, products, etc.

Programming in RPG IV Third Edition 6 Data Hierarchy File –Collection of data about a given kind of entity or object –Record –Collection of data about one specific instance of the entity Field –One piece of data on the record –Generally represents the smallest unit of data that we want to manipulate within a program.

Programming in RPG IV Third Edition 7 Programming Specifications Record Layouts –Input Processing required –Process Printer Spacing Charts –Output

Programming in RPG IV Third Edition 8 Printer Spacing Charts PSC NotationMeaning $XXXX.XXFixed dollar sign, no zero suppression, no comma $X,XX0.XXFixed dollar sign, zero-suppress to unit’s place, insert commas $X,XX$.XXFloating dollar sign, zero-suppress to unit’s place, insert commas XX0No currency symbol, complete zero-suppression XXXNo sign diplayed -XX0Fixed sign, complete zero suppression -XX-.XXFloating sign, zero suppress to unit’s place XX0.XX-Trailing sign, zero-supress XX0.XXCR“CR” for negative value, zero-suppress

Programming in RPG IV Third Edition 9 Program Development Cycle Define the problem Design the solution Write the program Enter the program Test and debug the program Document the program Maintain the program

Programming in RPG IV Third Edition 10 Program Entry and Testing Start Enter/edit Source Compile Program Syntax Errors? Bind Program Run Program Logic Errors? Stop Yes

Programming in RPG IV Third Edition 11 Points to Remember RPG is a high-level programming language introduced by IBM in the early 1960s to provide an easy way to produce commonly needed business reports Variables enable programs to process different sets of data Data is typically organized in a hierarchy of files, records, and fields