Unit 1. RPG IV Introduction

Copyright IBM Corp. 1996, 2000 1-1

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Unit Objectives - RPG IV Introduction

After completing this unit, you should be able to:

• Describe the evolution of RPG as a high level language

• Explain the general purpose of each RPG IV specification type

• List the order of RPG IV specification entries in a program

• Describe the steps to code and test an RPG IV program

• List several unique features of the RPG language and discuss RPG ′sstrengths and weaknesses

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RPG in the Sixties

• 1960

• High Level Language

• Fixed-Logic Cycle

• Indicators

• Batch Oriented

• Card based machinesOL861105

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RPG II - RPG III

• 1970

• Mid-range Systems

− System/3− System/32− System/34− System/36

• Interactive applications

− Disk processing support

− Workstation support

• Structured program design for efficiency

• DBMS grew in sophistication

• System/38OL861110

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RPG/400

• 1990

• AS/400

• Enhancements

− New operation codes− Named constants− Initialization subroutines− Source code indentation

• Embed SQL statements in RPG codeOL861115

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What is RPG IV?

• Available beginning with V3R1• Component of ILE RPG for AS/400 Program Product• Expanded or eliminated language limits• Fulfill RPG programmers ′ requirements

− Longer field names− Free form expressions− Date/time calculations supported

• Positioned for future growth• ILE

− Part of OS/400 beginning with V2R3− More modularity

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Development Cycle

• Define the problem

• Design the solution

• Write the program

• Test and debug the program

• Document the program

• Maintain the programOL861125

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Describing a Programming Solution

• Print headings

• Read an employee record

• Do While more records exist:

− Count each employee record read− Write detail employee information− Read an employee record

• Print total number of employees

• End programOL861130

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RPG IV Specifications

• Seven types of Specifications:

(H) Control Specifications(F) File description Specifications(D) Definition Specifications(I) Input Specifications(C) Calculation Specifications(O) Output Specifications(P) Procedure Specifications

• Specific functions

• Optional

• Fixed-position / free-formOL861140

Print Program

�FFilename++IPEASFRlen+LKlen+AIDevice+.Keywords....................** ** Define the files **FEmp_Mast IF E DiskFEmp_ReportO E Printer

DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords++++++++Comments ** ** Define program work fields **D Count S 3 0

CL0N01Factor1+++++++Opcode&ExtFactor2+++++++Result++++++++Len++D+HiLoEq ** ** Process data records **C Read Emp_Mast ----40 ** ** Have we read a record? **C If NOT (*in40)C Eval Count = Count + 1C Write DetailC Endif

** ** At EOF, write total and terminate program by setting on LR **C If *In40C Write TotalC Eval *InLR = *ONC Endif

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CRTBNDRPG Compile Options

• GENLVL(10)

• OPTION()

− *XREF/*NOXREF− *GEN/*NOGEN− *SHOWCPY/*NOSHOWCPY− *NOSECLVL/*SECLVL− *EXPDDS/*NOEXPDDS− *EXT/*NOEXT

• DBGVIEW(*STMT)

• OUTPUT(*PRINT/*NONE)

• INDENT(*NONE)

• REPLACE(*YES)

• TRUNCNBR(*YES)

• TGTRLS(*CURRENT)OL861165

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Compiler Dire ctives

• Format the listing

/TITLE/EJECT/SPACE

• Include other members in the compilation

/COPY

• Conditionally include / exclude code

/DEFINE/UNDEFINE

• Documentation / readability

*OL861175

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OL861205

Output Report

�Page: 1 EMPLOYEE INFORMATION

NAME SERIAL # DEPT TYPE

Haas 000010 A00 REGULARThompson 000020 B01 MANAGERKwan 000030 C01 MANAGERGeyer 000050 E01 MANAGERStern 000060 D11 MANAGERPulaski 000070 D21 MANAGERHenderson 000090 E11 MANAGERSpenser 000100 E21 MANAGERLucchesi 000110 A00 REGULARO Connell 000120 A00 REGULARQuintana 000130 C01 REGULARNicholls 000140 C01 REGULARAdamson 000150 D11 REGULARPianka 000160 D11 REGULARYoshimura 000170 D11 REGULARScoutten 000180 D11 REGULARWalker 000190 D11 REGULARBrown 000200 D11 REGULARJones 000210 D11 REGULARLutz 000220 D11 REGULARJefferson 000230 D21 REGULARMarino 000240 D21 REGULARSmith 000250 D21 REGULARJohnson 000260 D21 REGULARPerez 000270 D21 REGULARSchneider 000280 E11 REGULARParker 000290 E11 REGULARSmith 000300 E11 REGULARSetrignt 000310 E11 REGULARMehta 000320 E21 REGULARLee 000330 E21 REGULARGounot 000340 E21 REGULAR

NUMBER OF EMPLOYEES 32

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Copyright IBM Corp. 1996, 2000 1-20

Using the RPG Logic Cycle

�FFilename++IPEASF.....L.....A.Device+.Keywords+++++++++++++++++++++++++

FEmpMaster IP E K DISKFQprint O F 132 PRINTER OFLIND(*in73)DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords++++++++CommentsDType S 8DCount S 3 0CL0N01Factor1+++++++Opcode&ExtFactor2+++++++Result++++++++Len++D+HiLoEqC Eval *in73 = *offC If *InLR = *offC If JOB = ′ MANAGER′C Eval Type = ′ MANAGER′C ElseC Eval Type = ′ REGULAR′C EndIfC Eval Count = Count + 1C EndIfOFilename++DF..N01N02N03Excnam++++B++A++Sb+Sa+........................OQprint H 1P 2 2O OR 73O 5 ′ Page:′O PAGE Z 10O 50 ′ EMPLOYEE INFORMATION′O H 1P 2 1O OR 73O 12 ′ NAME′O 34 ′ SERIAL #′O 45 ′ DEPT′O 56 ′ TYPE′O D 1O LastName 20O Empno 32O WorkDept 45O TYPE 60O T LR 1O 20 ′ NUMBER OF EMPLOYEES′O COUNT L 27

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Copyright IBM Corp. 1996, 2000 1-21

Using Full Procedural - Non-Cycle

�FFilename++IPEASF.....L.....A.Device+.Keywords+++++++++++++++++++++++++

FEmpMaster IF E Disk FEmpReport O E Printer OflInd(*IN73)

** CL0N01Factor1+++++++Opcode&ExtFactor2+++++++Result++++++++Len++D+HiLoEq

** �1� Write report heading and read first recordC Write HeadingC Read Employee ----40 ** �2� Read the file and process until EOF using a loopC DoW *in40 = *OFFC Eval Count=Count + 1C Eval Name = %trimr(Lastname) **C IF Job = ′ MANAGER′C Eval Type = ′ MANAGER′C ELSEC Eval Type = ′ REGULAR′C EndIf ** �3� Check if overflowC If *in73 = *ONC Write HeadingC Eval *in73 = *offC EndIf ** �4� Write record to report and read next recordC Write DetailC Read Employee ----40C EndDo ** �5� Perform EOJC Write TotalC Eval *inlr = *on

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Unit Summary

Having completed this unit, you should be able to:

• Describe the evolution of RPG as a high level language

• Explain the general purpose of each RPG IV specification type

• List the order of RPG IV specification entries in a program

• Describe the steps to code and test an RPG IV program

• List several unique features of the RPG language and discuss RPG ′sstrengths and weaknesses

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