Free Form RPG

Overview

All RPG specs have free-form support except I and O specs.

Each free-form statement begins with an operation code and ends with a semicolon. Here is a list of the new operation codes:

• CTL-OPT for control specs (H)
• DCL-F for file specs (F)
• DCL-S, DCL-DS, DCL-SUBF, DCL-C, DCL-PR, DCL-PI, DCL-PARM for data specs (D)
• DCL-PROC for procedure specs (P)

Advantages

• Free-form RPG allows code to be specified as free-form statements rather than in specific fixed columns.
• Free-form code is still restricted to columns 8 – 80.
• The /FREE and /END-FREE compiler directives are tolerated, but are no longer required for free-form.
• Multiple line definitions are easier to code, easier to maintain, and easier to understand.
• Defining data items with long symbol names is no longer problematic.
• Free-form definitions can have /IF, /ELSEIF, /ELSE, and /ENDIF within the statement.

Changes for control specifications (H spec)

This section describes the changes for a control specification (H spec). The free-form keyword is CTL-OPT (Control Option). The free-form control statement starts with CTL-OPT, followed by zero or more keywords, and ends with a semicolon. Allowed keywords are the same keywords as an H spec.

Example Additional control statements

CTL-OPT OPTION(*SRCSTMT:*NODEBUGIO)

        DFTACTGRP(*No);

    // intermixed free-form and fixed-form

    CTL-OPT DATFMT(*ISO);

H TIMFMT(*ISO)

Changes for declaration statements (D spec)

This section describes the changes for declaration statements (D spec). A free-form data definition statement starts with DCL-<x>, and is followed by the data item name (which can be *N if the data item is unnamed), then by an optional data type, and then by zero or more keywords, and finally ends with a semicolon.

Example Fixed-form and free-form keywords

D* fixed-form declarations

D string        S       50A VARYING

D date          S         D DATFMT(*MDY)

D obj           S         O CLASS(*JAVA:'MyClass')

D ptr           S         * PROCPTR

   

    // free-form declarations

    DCL-S string VARCHAR(50);

    DCL-S date DATE(*MDY);

    DCL-S obj OBJECT(*JAVA:'MyClass');

    DCL-S ptr POINTER(*PROC);

Named constants

A named constant declaration starts with DCL-C, and is then followed by the name, then by the optional keyword CONST, and then by the value and finally ends with a semicolon.

Example  Named constants

// without the optional CONST keyword

DCL-C lower_bound -50;

DCL-C max_count 200;

DCL-C start_letter 'A';

// with the optional CONST keyword

DCL-C upper_bound CONST(-50);

DCL-C min_count CONST(200);

DCL-C end_letter CONST('A');

Specifying the CONST keyword makes no difference in the meaning of the declaration.

Stand-alone fields

A stand-alone field declaration starts with DCL-S.

Example  Stand-alone fields

DCL-S first_name CHAR(10) INZ('John');

DCL-S last_name  VARCHAR(20);

DCL-S index PACKED(6);

DCL-S salary PACKED(8:2);

Example  Stand-alone fields with LIKE

// Define using the LIKE keyword

DCL-S cust_index LIKE(index);

//Specify length adjustment with LIKE keyword

DCL-S big_index LIKE(index : +6);

Example  Declarations using named constants

DCL-C name_len CONST(10);

DCL-S one CHAR(name_len);

DCL-S two VARCHAR(name_len);

DCL-C digits 10;

DCL-C positions 3;

DCL-S value PACKED(digits:positions);

Example  Data structures

// Program described data structure

DCL-DS data_str_1;

    emp_name CHAR(10);

    first_name CHAR(10);

    salary PACKED(8:2);

END-DS;

// Program described data structure

DCL-DS data_str_2;

    value VARCHAR(4);

    index INT(10);

END-DS data_str_2;

//Unnamed data structure

DCL-DS *N;

    item VARCHAR(40);

END-DS;

Example Data structure using LIKEREC

DCL-DS custoutput LIKEREC(custrec);

Example Data structure with END-DS

DCL-DS PRT_DS LEN(132) END-DS;

Example Two equivalent data structures (END-DS)

DCL-DS myrecord EXT;

END-DS;

DCL-DS myrecord EXT END-DS;

Example Data structure with the DCL-SUBF keyword

DCL-DS record_one;

    buffer CHAR(25);

    DCL-SUBF read INT(3);

END-DS;

Example Two equivalent data structures (OVERLAY)

D* fixed-form declaration

D myds          DS

D   subf1           11      15A

D   subf2                    5P 2   OVERLAY(myds)

D   subf3                   10A     OVERLAY(myds:100)

D   subf4                   15A     OVERLAY(myds:*NEXT)

   

    //free-form declaration

    DCL-DS myds;

        subf1 CHAR(5) POS(11);

        subf2 PACKED(5:2) POS(1);

        subf3 CHAR(10) POS(100);

        subf4 CHAR(15);

    END-DS;

The OVERLAY(dsname:*NEXT) keyword means the same as no OVERLAY keyword at all.

Procedure prototypes

A procedure prototype declaration starts with DCL-PR, and is followed by a name and then by zero or more keywords, and ends with a semicolon.

Example Cosine procedure prototype

DCL-PR cosine FLOAT(8) EXTPROC('cos');

    angle FLOAT(8) VALUE;

END-PR;

Example GetCurTotal procedure prototype

DCL-PR getCurTotal PACKED(31:3) END-PR;

Example Procedure prototype parameter with the DCL-PARM keyword

DCL-PR proc_one;

    buffer CHAR(25) CONST;

    DCL-PARM read INT(3) VALUE;

END-PR;

Example  Procedure interface without parameters

DCL-PI *N CHAR(10);

END-PI;

Example Procedure interface parameter with the DCL-PARM keyword

DCL-PI proc_one;

    buffer CHAR(25) CONST;

    DCL-PARM read INT(3) VALUE;

END-PI;

Changes for procedure specifications (P spec)

This section describes the changes for a procedure specification (P spec). The free-form procedure statement declaration starts with DCL-PROC, and is followed by a name, then by an optional return type, and then by zero or more keywords, and ends with a semicolon.

Example Procedure statement

DCL-PR SubProc1 VARCHAR(100) DIM(2);

    varchar1    VARCHAR(10) CONST;

    ucs1        UCS2(5) CONST;

    varucs1     VARUCS2(5) CONST;

    graph1      GRAPH(20) CONST;

    vgraph1     VARGRAPH(50) CONST;

    packed1     PACKED(10) CONST;

    binary1     BINDEC(2) CONST;

    uns1        UNS(3) CONST;

    float1      FLOAT(4) CONST;

END-PR;

Changes for file specifications (F spec)

This section describes the changes for a file specification (F spec). The free-form file definition statement starts with DCL-F, and is followed by a file name and then by zero or more keywords, and ends with a semicolon.

Example File definition statement

DCL-F dspf WORKSTN

            EXTDESC('TABF035001');

Example 23. File definition statement (with additional keywords)

DCL-F dspf WORKSTN(*EXT) USAGE(*INPUT:*OUTPUT)

            EXTDESC('TABF035001');