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IBM RPG
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==Example code== The following program receives a customer number as an input parameter and returns the name and address as output parameters. This is the most primitive version of RPG IV syntax. The same program is shown later with gradually more modern versions of the syntax and gradually more relaxed rules. <pre> * Historically RPG was columnar in nature, though free-formatting * was allowed under particular circumstances. * The purpose of various lines code are determined by a * letter code in column 6. * An asterisk (*) in column 7 denotes a comment line * "F" (file) specs define files and other i/o devices F ARMstF1 IF E K Disk Rename(ARMST:RARMST) * "D" (data) specs are used to define variables D pCusNo S 6p D pName S 30a D pAddr1 S 30a D pAddr2 S 30a D pCity S 25a D pState S 2a D pZip S 10a * "C" (calculation) specs are used for executable statements * Parameters are defined using plist and parm opcodes C *entry plist C parm pCusNo C parm pName C parm pAddr1 C parm pAddr2 C parm pCity C parm pState C parm pZip * The "chain" command is used for random access of a keyed file C pCusNo chain ARMstF1 * If a record is found, move fields from the file into parameters C if %found C eval pName = ARNm01 C eval pAddr1 = ARAd01 C eval pAddr2 = ARAd02 C eval pCity = ARCy01 C eval pState = ARSt01 C eval pZip = ARZp15 C endif * RPG makes use of switches. One switch "LR" originally stood for "last record" * LR flags the program and its dataspace as removable from memory C eval *InLR = *On </pre> The same program using free calculations available starting in V5R1: <pre> * "F" (file) specs define files and other i/o devices FARMstF1 IF E K Disk Rename(ARMST:RARMST) * "D" (data) specs are used to define variables and parameters * The "prototype" for the program is in a separate file * allowing other programs to call it /copy cust_pr * The "procedure interface" describes the *ENTRY parameters D getCustInf PI D pCusNo 6p 0 const D pName 30a D pAddr1 30a D pAddr2 30a D pCity 25a D pState 2a D pZip 10a /free // The "chain" command is used for random access of a keyed file chain pCusNo ARMstF1; // If a record is found, move fields from the file into parameters if %found; pName = ARNm01; pAddr1 = ARAd01; pAddr2 = ARAd02; pCity = ARCy01; pState = ARSt01; pZip = ARZp15; endif; // RPG makes use of switches. One switch "LR" originally stood for "last record" // LR actually flags the program and its dataspace as removable from memory. *InLR = *On; /end-free </pre> Assume the ARMSTF1 example table was created using the following SQL Statement: <syntaxhighlight lang="sql"> create table armstf1 (arcnum decimal(7,0), arname char(30), aradd1 char(30), aradd2 char(30), arcity char(25), arstte char(2), arzip char(10)) </syntaxhighlight> The same program using free calculations and embedded SQL: <pre> * RPG IV no longer requires the use of the *INLR indicator to terminate a program. * by using the MAIN keyword on the "H" (Header) spec, and identifying the "main" or * entry procedure name, the program will begin and end normally without using the * decades-old RPG Cycle and instead a more "C like" begin and end logic. H MAIN(getCustInf) * "D" (data) specs are used to define variables and parameters * The "prototype" for the program is in a separate file * allowing other programs to call it /copy cust_pr * The "procedure interface" describes the *ENTRY parameters P getCustInf B D getCustInf PI D pCusNo 6p 0 const D pName 30a D pAddr1 30a D pAddr2 30a D pCity 25a D pState 2a D pZip 10a /free exec sql select arName, arAddr1, arAdd2, arCity, arStte, arZip into :pName, :pAddr1, :pAddr2, :pCity, :pState, :pZip from ARMstF1 where arCNum = :pCusNo for fetch only fetch first 1 row only optimize for 1 row with CS; /end-free P GetCustInf E </pre> As of V7R1 of the operating system, the above program would not necessarily need the prototype in a separate file, so it could be completely written as: <syntaxhighlight lang="sql"> H main(GetCustInf) D ARMSTF1 E DS P GetCustInf B D GetCustInf PI extpgm('CUS001') D inCusNo like(arCNum) const D outName like(arName) D outAddr1 like(arAdd1) D outAddr2 like(arAdd2) D outCity like(arCity) D outState like(arStte) D outZip like(arZip) /free exec sql select arName, arAdd1, arAdd2, arCity, arStte, arZip into :outName, :outAddr1, :outAddr2, :outCity, :outState, :outZip from ARMSTF1 where arCNum = :inCusNo fetch first 1 row only with CS use currently committed; /end-free P GetCustInf E </syntaxhighlight> Lastly, if you apply the compiler PTFs related Technology Refresh 7 (TR7) to your 7.1 operating system, then the above program can be coded completely in free-form, as follows: <syntaxhighlight lang="sql"> ctl-opt main(GetCustInf); dcl-ds ARMSTF1 ext end-ds; dcl-proc GetCustInf; dcl-pi *n extpgm('CUS001'); inCusNo like(arCNum) const; outName like(arName); outAddr1 like(arAdd1); outAddr2 like(arAdd2); outCity like(arCity); outState like(arStte); outZip like(arZip); end-pi; exec sql select arName, arAdd1, arAdd2, arCity, arStte, arZip into :outName, :outAddr1, :outAddr2, :outCity, :outState, :outZip from ARMSTF1 where arCNum = :inCusNo fetch first 1 row only with CS use currently committed; return; end-proc; </syntaxhighlight>
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