IBM Informix 4GL Reference Manual

IBM Informix 4GL

Reference Manual

Version 7.31 January 2002 Part No. 000-8776

Note: Before using this information and the product it supports, read the information in the appendix entitled Notices.

This document contains proprietary information of IBM. It is provided under a license agreement and is protected by copyright law. The information contained in this publication does not include any product warranties, and any statements provided in this manual should not be interpreted as such. When you send information to IBM, you grant IBM a nonexclusive right to use or distribute the information in any way it believes appropriate without incurring any obligation to you. Copyright International Business Machines Corporation 1996, 2002. All rights reserved. US Government User Restricted RightsUse, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp.

ii IBM Informix 4GL Reference Manual

Table of Contents

Table of Contents

IntroductionIn This Introduction . . . . . . . . About This Manual . . . . . . . . . Organization of This Manual . . . . Types of Readers . . . . . . . . Software Dependencies . . . . . . Assumptions About Your Locale. . . Demonstration Database and Examples Accessing Databases from Within 4GL. Enhancements to Version 7.31 . . . . . Documentation Conventions . . . . . Typographical Conventions . . . . Icon Conventions . . . . . . . . Example-Code Conventions . . . . Syntax Conventions . . . . . . . Additional Documentation . . . . . . Documentation Included with 4GL . . On-Line Manuals . . . . . . . . On-Line Help . . . . . . . . . On-Line Error Messages. . . . . . Related Reading . . . . . . . . Informix Developer Network . . . . Informix Welcomes Your Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3 3 5 5 6 6 7 8 8 9 10 11 12 16 17 18 18 18 20 20 21

Chapter 1

Compiling INFORMIX-4GL Source FilesIn This Chapter . . . . . . . . . . . . . . . . . Two Implementations of INFORMIX-4GL . . . . . . . Runtime and Compile-Time Requirements . . . . . . Differences Between the C Compiler and RDS Versions . The C Compiler Version . . . . . . . . . . . . . The Five-Phase 4GL Compilation Process . . . . . . The Programmers Environment . . . . . . . . . Creating Programs in the Programmers Environment . . Creating Programs at the Command Line . . . . . . Program Filename Extensions . . . . . . . . . . The Rapid Development System . . . . . . . . . . . The Programmers Environment . . . . . . . . . Creating Programs in the Programmers Environment . . Creating Programs at the Command Line . . . . . . Program Filename Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 1-3 1-4 1-4 1-6 1-7 1-9 1-27 1-33 1-47 1-49 1-49 1-69 1-75 1-90

Chapter 2

The INFORMIX-4GL LanguageIn This Chapter . . . . . . . . . . . . . . . . . . . Language Features . . . . . . . . . . . . . . . . . Lettercase Insensitivity . . . . . . . . . . . . . . . Whitespace, Quotation Marks, Escape Symbols, and Delimiters Character Set . . . . . . . . . . . . . . . . . . 4GL Statements . . . . . . . . . . . . . . . . . Comments . . . . . . . . . . . . . . . . . . . Source-Code Modules and Program Blocks . . . . . . . . Statement Blocks . . . . . . . . . . . . . . . . . Statement Segments . . . . . . . . . . . . . . . . 4GL Identiers . . . . . . . . . . . . . . . . . Interacting with Users . . . . . . . . . . . . . . . . Ring Menus . . . . . . . . . . . . . . . . . . Screen Forms . . . . . . . . . . . . . . . . . . 4GL Windows . . . . . . . . . . . . . . . . . . On-Line Help . . . . . . . . . . . . . . . . . . Nested and Recursive Statements . . . . . . . . . . . Exception Handling . . . . . . . . . . . . . . . . . Compile-Time Errors and Warnings . . . . . . . . . . Runtime Errors and Warnings . . . . . . . . . . . . Changes to 4GL Error Handling . . . . . . . . . . . Error Handling with SQLCA . . . . . . . . . . . . 2-3 2-3 2-3 2-4 2-5 2-5 2-8 2-10 2-12 2-13 2-14 2-22 2-23 2-25 2-28 2-29 2-31 2-40 2-40 2-40 2-44 2-45

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IBM Informix 4GL Reference Manual

Chapter 3

Data Types and ExpressionsIn This Chapter . . . . . . . . . . . . . Data Values in 4GL Programs . . . . . . . . Data Types of 4GL . . . . . . . . . . . . Simple Data Types . . . . . . . . . . . Structured Data Types . . . . . . . . . Large Data Types . . . . . . . . . . . Descriptions of the 4GL Data Types . . . . . ARRAY . . . . . . . . . . . . . . BYTE . . . . . . . . . . . . . . . CHAR . . . . . . . . . . . . . . . CHARACTER . . . . . . . . . . . . DATE . . . . . . . . . . . . . . . DATETIME . . . . . . . . . . . . . DEC. . . . . . . . . . . . . . . . DECIMAL (p, s) . . . . . . . . . . . DECIMAL (p) . . . . . . . . . . . . DOUBLE PRECISION . . . . . . . . . FLOAT . . . . . . . . . . . . . . . INT . . . . . . . . . . . . . . . . INTEGER . . . . . . . . . . . . . . INTERVAL . . . . . . . . . . . . . MONEY . . . . . . . . . . . . . . NCHAR . . . . . . . . . . . . . . NVARCHAR. . . . . . . . . . . . . NUMERIC . . . . . . . . . . . . . REAL . . . . . . . . . . . . . . . RECORD . . . . . . . . . . . . . . SMALLFLOAT . . . . . . . . . . . . SMALLINT . . . . . . . . . . . . . TEXT . . . . . . . . . . . . . . . VARCHAR . . . . . . . . . . . . . Data Type Conversion . . . . . . . . . Summary of Compatible 4GL Data Types . . . Expressions of 4GL . . . . . . . . . . Differences Between 4GL and SQL Expressions . Components of 4GL Expressions . . . . . . Boolean Expressions . . . . . . . . . . Integer Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 3-5 3-6 3-9 3-12 3-12 3-12 3-13 3-14 3-16 3-17 3-17 3-18 3-23 3-23 3-24 3-25 3-25 3-26 3-26 3-27 3-32 3-33 3-34 3-34 3-34 3-35 3-37 3-38 3-39 3-40 3-42 3-46 3-49 3-51 3-52 3-60 3-63 v

Table of Contents

Number Expressions . . . . . . . . . . . . . . . Character Expressions . . . . . . . . . . . . . . . Time Expressions. . . . . . . . . . . . . . . . . Field Clause . . . . . . . . . . . . . . . . . . Table Qualiers . . . . . . . . . . . . . . . . . THRU or THROUGH Keywords and .* Notation . . . . . ATTRIBUTE Clause . . . . . . . . . . . . . . . .

3-66 3-69 3-72 3-86 3-89 3-92 3-96

Chapter 4

INFORMIX-4GL StatementsIn This Chapter . . . . . . . The 4GL Statement Set . . . . Types of SQL Statements . . Other Types of 4GL Statements Statement Descriptions . . . . CALL . . . . . . . . . CASE . . . . . . . . . CLEAR . . . . . . . . CLOSE FORM . . . . . . CLOSE WINDOW . . . . CONSTRUCT . . . . . . CONTINUE . . . . . . CURRENT WINDOW . . . DATABASE. . . . . . . DEFER . . . . . . . . DEFINE . . . . . . . . DISPLAY . . . . . . . DISPLAY ARRAY . . . . DISPLAY FORM . . . . . END . . . . . . . . . ERROR . . . . . . . . EXIT . . . . . . . . . FINISH REPORT . . . . . FOR . . . . . . . . . FOREACH . . . . . . . FUNCTION . . . . . . GLOBALS . . . . . . . GOTO . . . . . . . . IF . . . . . . . . . . INITIALIZE . . . . . . INPUT . . . . . . . . INPUT ARRAY . . . . . LABEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9 4-9 4-9 4-13 4-15 4-16 4-22 4-28 4-31 4-32 4-34 4-66 4-68 4-71 4-78 4-81 4-90 4-102 4-113 4-116 4-118 4-121 4-125 4-128 4-131 4-140 4-145 4-151 4-153 4-155 4-159 4-187 4-224

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LET . . . . . . . LOAD . . . . . . LOCATE . . . . . MAIN . . . . . . MENU . . . . . . MESSAGE . . . . NEED . . . . . . OPEN FORM . . . OPEN WINDOW . . OPTIONS . . . . . OUTPUT TO REPORT PAUSE . . . . . . PREPARE . . . . . PRINT . . . . . . PROMPT . . . . . REPORT . . . . . RETURN . . . . . RUN . . . . . . SCROLL . . . . . SKIP . . . . . . SLEEP . . . . . . SQL . . . . . . . START REPORT . . TERMINATE REPORT UNLOAD . . . . . VALIDATE . . . . WHENEVER. . . . WHILE. . . . . .

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4-226 4-230 4-239 4-245 4-248 4-273 4-276 4-278 4-280 4-291 4-308 4-311 4-312 4-324 4-325 4-332 4-337 4-340 4-344 4-346 4-348 4-349 4-354 4-364 4-367 4-372 4-376 4-382

Chapter 5

Built-In Functions and OperatorsIn This Chapter . . . . . . . . . . . . . . . . . . Functions in 4GL Programs . . . . . . . . . . . . . . Built-In 4GL Functions . . . . . . . . . . . . . . Built-In and External SQL Functions and Procedures . . . . C Functions . . . . . . . . . . . . . . . . . . ESQL/C Functions . . . . . . . . . . . . . . . Programmer-Dened 4GL Functions . . . . . . . . . Invoking Functions . . . . . . . . . . . . . . . Operators of 4GL . . . . . . . . . . . . . . . . . Built-In Functions of Informix Dynamic 4GL . . . . . . . . 5-5 5-5 5-6 5-7 5-7 5-7 5-8 5-9 5-11 5-12

Table of Contents vii

Syntax of Built-In Functions and Operators Aggregate Report Functions . . . . ARG_VAL( ) . . . . . . . . . Arithmetic Operators . . . . . . ARR_COUNT( ) . . . . . . . . ARR_CURR( ) . . . . . . . . . ASCII . . . . . . . . . . . Boolean Operators . . . . . . . CLIPPED . . . . . . . . . . COLUMN . . . . . . . . . . Concatenation ( || ) Operator . . . CURRENT . . . . . . . . . . CURSOR_NAME( ) . . . . . . . DATE . . . . . . . . . . . . DAY( ) . . . . . . . . . . . DOWNSHIFT( ) . . . . . . . . ERR_GET( ) . . . . . . . . . ERR_PRINT( ) . . . . . . . . ERR_QUIT( ) . . . . . . . . . ERRORLOG( ) . . . . . . . . . EXTEND( ) . . . . . . . . . . FGL_DRAWBOX( ) . . . . . . . FGL_GETENV( ) . . . . . . . . FGL_GETKEY( ) . . . . . . . . FGL_KEYVAL( ) . . . . . . . . FGL_LASTKEY( ) . . . . . . . FGL_SCR_SIZE( ) . . . . . . . FGL_SETCURRLINE ( ) . . . . . FIELD_TOUCHED( ) . . . . . . GET_FLDBUF( ) . . . . . . . . INFIELD( ) . . . . . . . . . . LENGTH( ) . . . . . . . . . LINENO. . . . . . . . . . . MDY( ) . . . . . . . . . . . Membership ( . ) Operator. . . . . MONTH( ) . . . . . . . . . . NUM_ARGS( ) . . . . . . . . ORD( ) . . . . . . . . . . . PAGENO . . . . . . . . . . SCR_LINE( ) . . . . . . . . . SET_COUNT( ) . . . . . . . . SHOWHELP( ) . . . . . . . . SPACE . . . . . . . . . . . viii IBM Informix 4GL Reference Manual

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5-13 5-14 5-18 5-20 5-27 5-29 5-31 5-33 5-45 5-47 5-50 5-51 5-53 5-56 5-58 5-59 5-61 5-63 5-64 5-65 5-67 5-70 5-73 5-75 5-76 5-78 5-81 5-83 5-84 5-87 5-90 5-92 5-94 5-95 5-97 5-98 5-99 5-100 5-101 5-102 5-104 5-106 5-108

STARTLOG( ) . . . . Substring ( [ ] ) Operator. TIME . . . . . . . TODAY . . . . . . UNITS . . . . . . . UPSHIFT( ) . . . . . USING . . . . . . WEEKDAY( ) . . . . WORDWRAP . . . . YEAR( ) . . . . . .

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5-110 5-113 5-116 5-117 5-119 5-121 5-123 5-133 5-135 5-138

Chapter 6

Screen FormsIn This Chapter . . . . . . . . . . . . . 4GL Forms . . . . . . . . . . . . . . . Form Drivers . . . . . . . . . . . . Form Fields . . . . . . . . . . . . . Structure of a Form Specication File . . . . . . DATABASE Section . . . . . . . . . . . . Database References in the DATABASE Section. The FORMONLY Option . . . . . . . . The WITHOUT NULL INPUT Option . . . . SCREEN Section . . . . . . . . . . . . . The SIZE Option . . . . . . . . . . . The Screen Layout . . . . . . . . . . . Display Fields . . . . . . . . . . . . Literal Characters in Forms. . . . . . . . TABLES Section . . . . . . . . . . . . . Table Aliases . . . . . . . . . . . . . ATTRIBUTES Section . . . . . . . . . . . FORMONLY Fields . . . . . . . . . . Multiple-Segment Fields . . . . . . . . Field Attributes . . . . . . . . . . . Field Attribute Syntax . . . . . . . . . AUTONEXT . . . . . . . . . . . . . CENTURY . . . . . . . . . . . . . COLOR . . . . . . . . . . . . . . COMMENTS . . . . . . . . . . . . DEFAULT . . . . . . . . . . . . . DISPLAY LIKE . . . . . . . . . . . . DOWNSHIFT . . . . . . . . . . . . FORMAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5 6-5 6-5 6-7 6-9 6-12 6-13 6-14 6-14 6-15 6-16 6-17 6-17 6-19 6-23 6-24 6-25 6-29 6-31 6-32 6-33 6-34 6-35 6-37 6-43 6-45 6-48 6-49 6-50

Table of Contents ix

INCLUDE . . . . . . . . . . . . . . . . . . . INVISIBLE . . . . . . . . . . . . . . . . . . . NOENTRY . . . . . . . . . . . . . . . . . . . PICTURE . . . . . . . . . . . . . . . . . . . PROGRAM . . . . . . . . . . . . . . . . . . REQUIRED . . . . . . . . . . . . . . . . . . REVERSE . . . . . . . . . . . . . . . . . . . UPSHIFT . . . . . . . . . . . . . . . . . . . VALIDATE LIKE . . . . . . . . . . . . . . . . . VERIFY . . . . . . . . . . . . . . . . . . . . WORDWRAP . . . . . . . . . . . . . . . . . . INSTRUCTIONS Section . . . . . . . . . . . . . . . Screen Records . . . . . . . . . . . . . . . . . Screen Arrays . . . . . . . . . . . . . . . . . . Field Delimiters . . . . . . . . . . . . . . . . . Default Attributes . . . . . . . . . . . . . . . . . . Precedence of Field Attribute Specications . . . . . . . Default Attributes in an ANSI-Compliant Database . . . . . Creating and Compiling a Form . . . . . . . . . . . . . Compiling a Form Through the Programmers Environment . Compiling a Form at the Command Line . . . . . . . . Default Forms . . . . . . . . . . . . . . . . . . Using PERFORM Forms in 4GL . . . . . . . . . . . . .

6-53 6-56 6-57 6-58 6-60 6-62 6-63 6-64 6-65 6-66 6-67 6-74 6-74 6-77 6-79 6-80 6-83 6-84 6-85 6-85 6-87 6-89 6-91

Chapter 7

INFORMIX-4GL ReportsIn This Chapter . . . . . . . . . . . . . . . . . Features of 4GL Reports . . . . . . . . . . . . . . Producing 4GL Reports . . . . . . . . . . . . . . The Report Driver . . . . . . . . . . . . . . The Report Denition . . . . . . . . . . . . . DEFINE Section . . . . . . . . . . . . . . . . OUTPUT Section . . . . . . . . . . . . . . . . ORDER BY Section . . . . . . . . . . . . . . . FORMAT Section . . . . . . . . . . . . . . . . EVERY ROW . . . . . . . . . . . . . . . . FORMAT Section Control Blocks . . . . . . . . . . Statements Prohibited in FORMAT Section Control Blocks AFTER GROUP OF . . . . . . . . . . . . . . BEFORE GROUP OF . . . . . . . . . . . . . FIRST PAGE HEADER . . . . . . . . . . . . . ON EVERY ROW. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3 7-4 7-5 7-5 7-7 7-10 7-12 7-23 7-28 7-29 7-32 7-33 7-34 7-37 7-40 7-42

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ON LAST ROW. . . . . . . . . . . PAGE HEADER . . . . . . . . . . PAGE TRAILER . . . . . . . . . . Statements in REPORT Control Blocks . . . . Statements Valid Only in the FORMAT Section EXIT REPORT . . . . . . . . . . . NEED . . . . . . . . . . . . . . PAUSE . . . . . . . . . . . . . . PRINT . . . . . . . . . . . . . . SKIP . . . . . . . . . . . . . .

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7-44 7-45 7-47 7-48 7-49 7-50 7-52 7-54 7-55 7-68

Appendix A Appendix B Appendix C Appendix D Appendix E Appendix F Appendix G Appendix H Appendix I Appendix J

The ASCII Character Set INFORMIX-4GL Utility Programs Using C with INFORMIX-4GL Environment Variables Developing Applications with Global Language Support Modifying termcap and terminfo Reserved Words The Demonstration Application SQL Statements That Can Be Embedded in 4GL Code Notices Glossary Index

Table of Contents xi

Introduction

Introduction

In This Introduction

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3 3 3 5 5 6 6 7 8 8 9 10 10 10 11 12 13 15 16 17 18 18 18 20 20 21

About This Manual . . . . . . . . . Organization of This Manual . . . . Types of Readers . . . . . . . . Software Dependencies . . . . . . Assumptions About Your Locale . . . Demonstration Database and Examples Accessing Databases from Within 4GL . Enhancements to Version 7.31 . . . . .

Documentation Conventions . . . . . . Typographical Conventions . . . . . Icon Conventions . . . . . . . . . Feature, Product, and Platform Icons . Compliance Icons . . . . . . . Example-Code Conventions . . . . . Syntax Conventions . . . . . . . . Elements That Can Appear on the Path How to Read a Syntax Diagram . . . Additional Documentation . . . . Documentation Included with 4GL On-Line Manuals . . . . . . On-Line Help . . . . . . . On-Line Error Messages. . . . Related Reading . . . . . . Informix Developer Network . . Informix Welcomes Your Comments . . . . . . . . . . . . . . . . . . . . . . . . .

2


In This IntroductionThis Introduction provides an overview of the information in this manual and describes the conventions it uses.

About This ManualThis manual is designed to be a day-to-day, keyboard-side companion for 4GL programmers. It describes the features and syntax of the 4GL language, including 4GL statements, forms, reports, and the built-in functions and operators.

Organization of This ManualThis manual is divided into two volumes and includes the following chapters and appendixes:s

Chapter 1, Compiling INFORMIX-4GL Source Files, describes the C Compiler and Rapid Development System implementations of INFORMIX-4GL. It also explains how to create executable versions of 4GL source les, both from the Programmers Environment and from the command line. Chapter 2, The INFORMIX-4GL Language, provides an overview of 4GL language features and graphical features of the applications that you can create with INFORMIX-4GL. Chapter 3, Data Types and Expressions, describes 4GL data types, expressions, and other syntax topics that affect several statements.

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Introduction 3

Organization of This Manual

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Chapter 4, INFORMIX-4GL Statements, describes the statements of 4GL in alphabetical order. Chapter 5, Built-In Functions and Operators, includes an overview of the predened functions and operators of 4GL and describes their individual syntax, with examples of usage. Chapter 6, Screen Forms, provides an overview of 4GL screen forms and form drivers and describes the syntax of 4GL form specication les. It also describes how to create forms with the form4gl form compiler and describes how the upscol utility can set default attributes. Chapter 7, INFORMIX-4GL Reports, offers an overview of 4GL reports and report drivers, and describes the syntax of 4GL report denitions. It also describes the syntax of statements and operators that can appear only in 4GL reports. Appendix A, The ASCII Character Set, lists the ASCII characters and their numeric codes. Appendix B, INFORMIX-4GL Utility Programs, describes the mkmessage and upscol utility programs. Appendix C, Using C with INFORMIX-4GL, describes how to call C functions from 4GL programs, and vice versa, and describes a function library for conversion between the DECIMAL data type of 4GL and the C data types. Appendix D, Environment Variables, describes the environment variables that are used by 4GL. Appendix E, Developing Applications with Global Language Support, describes the internationalization and localization features that are provided with 4GL, and shows how to develop 4GL applications that are world-ready and easy to localize. Appendix F, Modifying termcap and terminfo, describes the modications you can make to your termcap and terminfo les to extend function key denitions, to specify characters for window borders, and to enable 4GL programs to interact with terminals that support color displays. Appendix G, Reserved Words, lists words that you should not declare as identiers in 4GL programs. It also lists the ANSI reserved words of SQL.

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Types of Readers

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Appendix H, The Demonstration Application, lists the code of the demo4.4ge demonstration application. Appendix I, SQL Statements That Can Be Embedded in 4GL Code, lists SQL syntax that is directly supported in 4GL. A Notices appendix describes IBM products, features, and services. The Glossary denes terms used in the 4GL documentation set.

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Types of ReadersThis manual is written for all 4GL developers. You do not need database management experience nor familiarity with relational database concepts to use this manual. A knowledge of SQL (structured query language), however, and experience using a high-level programming language would be useful.

Software DependenciesThis manual is written with the assumption that you are using an Informix database server, Version 7.x or later. Informix offers two implementations of the 4GL application development language:s

The INFORMIX-4GL C Compiler uses a preprocessor to generate Informix ESQL/C source code. This code is preprocessed in turn to produce C source code, which is then compiled and linked as object code in an executable command le. The INFORMIX-4GL Rapid Development System (RDS) uses a compiler to produce pseudo-machine code (called p-code) in a single step. You then invoke a runner to execute the p-code version of your application.

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Both versions of 4GL use the same 4GL statements. Chapter 1, Compiling INFORMIX-4GL Source Files, describes the differences between the two versions of 4GL and explains how to use both versions. You can easily use applications developed with an earlier version of 4GL, such as Version 4.x or 6.x or 7.2, with this version of 4GL. For RDS programs that use p-code, however, you must rst recompile your 4GL source code.

Introduction 5

Assumptions About Your Locale

Assumptions About Your LocaleInformix products can support many languages, cultures, and code sets. All culture-specic information is brought together in a single environment, called a GLS (Global Language Support) locale. Examples in this manual are written with the assumption that you are using the default locale, en_us.8859-1. This supports U.S. English format conventions for dates, times, and currency, and the ISO 8859-1 code set. Some versions of this locale support various non-ASCII 8-bit characters such as , , and . Like all locales that Informix provides with its GLS libraries, however, the default locale supports the ASCII characters (as listed in Appendix A). If you plan to use non-ASCII characters in your data or your SQL identiers, or if you want nondefault collation of character data, you need to specify the appropriate nondefault locale. For instructions on how to specify a nondefault locale, additional syntax, and other considerations related to GLS, see the Informix Guide to GLS Functionality. See also Appendix E, Developing Applications with Global Language Support.

Demonstration Database and Examples4GL includes several 4GL demonstration applications, along with a demon-

stration database called stores7 that contains information about a ctitious wholesale sporting-goods distributor. You can create the stores7 database in the current directory by entering the following command:dbaccessdemo7

Many (but not all) of the examples in the 4GL documentation set are based on the stores7 database. This database is described in detail in Appendix A of INFORMIX-4GL by Example. For more information on creating the demonstration database and using the examples, see the introduction to INFORMIX4GL by Example.

6


Accessing Databases from Within 4GL

Accessing Databases from Within 4GLThe 4GL language approximates a superset of the Informix implementation of the industry-standard SQL language. Because the 4GL compiler does not recognize some SQL statements, however, three methods are supported for including SQL statements within the 4GL program:s

For most SQL syntax that was supported by Informix 4.1 database servers, you can directly embed SQL statements in 4GL source code. For SQL statements that can be prepared, you can use the PREPARE feature of SQL to include SQL statements as text in prepared objects. For all SQL statements that can be prepared, you can also use the SQL ... END SQL delimiters to enclose the SQL statement. Unlike PREPARE, these can include host variables for input and output.

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You must use one of the last two methods for SQL statements that include syntax that was introduced later than Informix 4.1 database servers. Such embedded, prepared, or delimited SQL statements are passed on to the database server for execution, as in the following 4GL program fragment:DEFINE bugfile, setdeb CHAR(255) DATABASE stores7 --Directly embedded SQL LET setdeb = "set debug file to /u/tanya/bugfile" PREPARE bugfile FROM setdeb --Prepared SQL (post-4.1) EXECUTE IMMEDIATE bugfile --Directly embedded SQL SQL SET PDQPRIORITY HIGH --Delimited SQL (post-4.1) END SQL

Appendix I, SQL Statements That Can Be Embedded in 4GL Code, lists the supported SQL syntax. If you are uncertain which method is needed, use SQLEND SQL delimiters, which generally offer wider functionality and greater ease of coding than PREPARE for SQL statements that cannot be directly embedded. For additional information on SQL statements, see Informix Guide to SQL: Syntax.

Introduction 7

Enhancements to Version 7.31

Enhancements to Version 7.31This product includes the following enhancements:s

The NCHAR and NVARCHAR data types are now recognized and supported. For information about the NCHAR and NVARCHAR data types, see Chapter 3, Data Types and Expressions, of this book. For database servers that support long SQL identiers, your 4GL applications can reference SQL identiers that are up to 128 bytes in length. For more information about IFX_LONGID, see Chapter 2, The INFORMIX-4GL Language, of this book.IBM INFORMIX-4GL is compatible with IBM Informix Client SDK 2.70.xC3 and above. Client SDK components allow developers to write applications in the language they are familiar with, whether it be Java, C++, C, or ESQL. For more information about Client SDK, see the documentation set at www.informix.com/answers.

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Documentation ConventionsThis section describes certain conventions that this manual uses. These conventions make it easier to gather information from this and other volumes in the documentation set. The following conventions are discussed:s s s s

Typographical conventions Icon conventions Example-code conventions Syntax conventions

8


Typographical Conventions

Typographical ConventionsThis manual uses the following conventions to introduce new terms, illustrate screen displays, describe command syntax, and so forth.Convention KEYWORD italics italicsitalics

Meaning All primary elements in a programming language statement (keywords) appear in uppercase letters in a serif font. Within text, new terms and emphasized words appear in italics. Within syntax diagrams and code examples, identiers or values that you are to specify appear in italics. Names of program entities (such as classes, events, and tables), environment variables, le and pathnames, and interface elements (such as icons, menu items, and buttons) appear in boldface. Information that the product displays and information that you enter appear in a monospace typeface. Keys to press appear in uppercase letters in a sans serif font.

boldface boldface

monospace monospace KEYSTROKE

Tip: When you are instructed to enter characters or to execute a command, immediately press RETURN after the entry. When you are instructed to type the text or to press other keys, no RETURN is required.

Introduction 9

Icon Conventions

Icon ConventionsThroughout the documentation, you will nd text that is identied by several different types of icons. This section describes these icons.

Feature, Product, and Platform IconsFeature, product, and platform icons identify paragraphs that contain feature-specic, product-specic, or platform-specic information.IconGLS

Description Identies information that relates to the Informix Global Language Support (GLS) feature. Identies information or syntax that is specic to Informix Dynamic Server. Identies information or syntax that is specic to INFORMIX-SE. Identies SQL statements that you must put in an SQL block or prepare statement.

IDS

SE

SQL

These icons can apply to a row in a table, one or more paragraphs, or an entire section. A symbol indicates the end of the feature-specic, productspecic, or platform-specic information.

Compliance IconsCompliance icons indicate paragraphs that provide guidelines for complying with a standard.IconANSI

Description Identies information that is specic to an ANSI-compliant database

These icons can apply to a row in a table, one or more paragraphs, or an entire section. A symbol indicates the end of the compliance information.10 IBM Informix 4GL Reference Manual

Example-Code Conventions

Example-Code ConventionsExamples of 4GL source code occur in several sections of this manual. For readability, 4GL or SQL keywords generally appear in uppercase characters in code examples, and identiers usually appear in lowercase or mixed case. For instance, you might see code as in the following example:MENU "CUSTOMER" COMMAND "Query" "Search for a customer" CALL query_data( ) NEXT OPTION "Modify" ... COMMAND "Modify" "Modify a customer" ... END MENU

Ellipsis ( ) symbols in a code example indicate that more code would be added in a complete application, but for clarity and simplicity, the example omits code that is extraneous to the current topic. (In most contexts, a compile-time or runtime error occurs if literal ellipsis symbols appear in code, or if you omit code that is necessary to your program logic.) Ellipsis symbols do not begin or end code examples, however, even if additional code would be required for a complete program, or for a complete statement. Most 4GL code examples are fragments of programs, rather than complete programs that can be compiled and executed. Because most examples are provided to illustrate some specic topic, the examples sometimes do not strictly conform to good programming practice. For example, they might not check to verify that an operation successfully executed without error, or they might not include the comments that normally should be included to improve readability and simplify maintenance of your code.

Introduction 11

Syntax Conventions

Syntax ConventionsSQL statement syntax is described in the Informix Guide to SQL: Syntax. The syntax for 4GL statements is described in Chapter 4 of this manual. Most chapters of this book describe the syntax of some aspect of the 4GL language,

such as expressions, form specications, and reports. This section describes conventions for syntax diagrams. Each diagram displays the sequences of required and optional keywords, terms, and symbols that are valid in a given statement or segment. Figure 1 shows the syntax diagram of the OPEN FORM statement.Figure 1 Example of a Simple Syntax DiagramOPEN FORM form FROM "lename"

Each syntax diagram begins at the upper-left corner and ends at the upperright corner with a vertical terminator. Between these points, any path that does not stop or reverse direction describes a possible form of the statement. (For a few diagrams, however, notes in the text identify path segments that are mutually exclusive.) Syntax elements in a path represent terms, keywords, symbols, and segments that can appear in your statement. The path always approaches elements from the left and continues to the right, except in the case of separators in loops. For separators in loops, the path approaches counterclockwise. Unless otherwise noted, at least one blank character separates syntax elements.

12


Syntax Conventions

Elements That Can Appear on the PathYou might encounter one or more of the following elements on a path.Element KEYWORD Description A word in UPPERCASE letters is a keyword. You must spell the word exactly as shown; you can, however, use either uppercase or lowercase letters. Punctuation and other nonalphanumeric characters are literal symbols that you must enter exactly as shown. Double quotation marks must be entered as shown. If you prefer, a pair of double quotation marks can replace a pair of single quotation marks, but you cannot mix double and single quotation marks. A word in italics represents a value that you must supply. A table that follows the diagram explains the value. A reference in a box represents a subdiagram. Imagine that the subdiagram is spliced into the main diagram at this point. When a page number is not specied, the subdiagram appears on the same page. The aspect ratios of boxes are not signicant. A reference to SQL:S in a syntax diagram represents an SQL statement or segment that is described in the Informix Guide to SQL: Syntax. Imagine that the segment were spliced into the diagram at this point. An icon is a warning that this path is valid only for some products, or conditions. The following icons appear in some syntax diagrams:SE

(.,;@+*-/)

" " ' ' variable

ATTRIBUTE Clause p. 3-288 ATTRIBUTE Clause

SELECT Statement see SQL:S

SE

This path is valid only for INFORMIX-SE database servers. This path is valid only for Informix Dynamic Server. (1 of 2)

IDS

Introduction 13

Syntax Conventions

Element

Description+

This path produces a warning (of a syntax extension to the ANSI/ISO standard for SQL) if DBANSIWARN is set, or if the program is compiled with the -ansi ag.

ALL

A shaded option is the default, if you provide no other specication.

...

A syntax segment within a pair of arrows is a subdiagram. The vertical line terminates the syntax diagram.

IS NOT NOT FOUND ERROR WARNING

NULL

A branch below the main path indicates an optional path. (Any term on the main path is required, unless a branch can circumvent it.) A set of multiple branches indicates that a choice among more than two different paths is available.

,variable statement

A loop indicates a path that you can repeat. Punctuation along the top of the loop indicates the separator symbol for list items. If no symbol appears, a blank space is the separator, or (as here) the Linefeed that separates successive statements in a source module. A gate ( 3 ) on a path indicates that you can only use that path the indicated number of times, even if it is part of a larger loop. You can specify size no more than three times within this statement segment. (2 of 2)

,3 size

14


Syntax Conventions

How to Read a Syntax DiagramFigure 2 shows a syntax diagram that uses some of the path elements that the previous table lists.Figure 2 Example of a Syntax Diagram Case III: (display output in a screen form)

,DISPLAY value TO

,Field Clause

,BY NAME variable

ATTRIBUTE Clause

The Case III label above the diagram implies that this statement can have at least two other syntax patterns. To use this diagram to construct a statement, start at the top left with the keyword DISPLAY. Then follow the diagram to the right, proceeding through the options that you want. Figure 2 illustrates the following steps:1. 2.

Type the keyword DISPLAY. You can display the values of a list of variables to an explicit list of elds within the current screen form:s

Type the name of a value. If you want to display several values, separate successive values by a comma. Type the keyword TO after the name of the last value. Type the name of a eld in the current form in which to display the rst value. To nd the syntax for specifying eld names, go to the Field Clause segment on the specied page.

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3.

If you are using a form whose elds have the same names as the values that you want to display, you can follow the lower path:s s

Type the keywords BY NAME after DISPLAY. Type the name of a variable. If you want to display the values of several variables, separate successive variables by comma.

Introduction 15

Additional Documentation

4.

You can optionally set a screen attribute for the displayed values:s

Use the syntax of the ATTRIBUTE Clause segment on the specied page to specify the screen attribute that you desire.

5.

Follow the diagram to the terminator. Your DISPLAY TO or DISPLAY BY NAME statement is now complete. A restriction on step 2 (that there must be as many elds as variables) appears in notes that follow the diagram, rather than in the diagram itself. If 4GL issues an error when you compile a statement that seems to follow the syntax diagram, it might be a good idea to also read the usage notes for that statement.

Additional DocumentationFor additional information, you might want to refer to the following types of documentation:s s s s s

Documentation included with 4GL On-line manuals On-line help On-line error messages Related reading

16


Documentation Included with 4GL

Documentation Included with 4GLThe INFORMIX-4GL documentation set includes the following additional manuals:s

INFORMIX-4GL Installation Guide is a pamphlet that describes how to install the various 4GL products. INFORMIX-4GL Concepts and Use introduces 4GL and provides the

s

context needed to understand the other manuals in the documentation set. It covers 4GL goals (what kinds of programming the language is meant to facilitate), concepts and nomenclature (parts of a program, ideas of database access, screen form, and report generation), and methods (how groups of language features are used together to achieve particular effects).s

INFORMIX-4GL by Example is a collection of 30 annotated 4GL

programs. Each is introduced with an overview; then the program source code is shown with line-by-line notes. The program source les are distributed as text les with the product; scripts that create the demonstration database and copy the applications are also included.s

Documentation notes, which contain additions and corrections to the manuals, and release notes are located in the directory where the product is installed. Please examine these les because they contain vital information about application and performance issues.

If you have also purchased the INFORMIX-4GL Interactive Debugger product (which requires the INFORMIX-4GL Rapid Development System), your 4GL documentation also includes the following manual:s

Guide to the INFORMIX-4GL Interactive Debugger is both an introduction to the Debugger and a comprehensive reference of Debugger commands and features. The Debugger allows you view the source code and to interact with your 4GL programs while they are running. It helps you to analyze the logic of your 4GL program and to determine the source of runtime errors within your programs.

Introduction 17

On-Line Manuals

On-Line ManualsThe Informix Answers OnLine CD allows you to print chapters or entire books and perform full-text searches for information in specic books or throughout the documentation set. You can install the documentation or access it directly from the CD. For information about how to install, read, and print on-line manuals, see the installation insert that accompanies Answers OnLine. You can also access Answers OnLine on the Web at the following URL:http://www.informix.com/answers

On-Line HelpThe Programmers Environment of 4GL provides on-line help; you can invoke help by pressing CONTROL-W.

On-Line Error MessagesUse the nderr script to display a particular error message or messages on your screen. The script is located in the $INFORMIXDIR/bin directory.

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On-Line Error Messages

The nderr script has the following syntax.

nderr

msg_num

msg_num

Indicates the number of the error message to display. Error message numbers range from -1 to -32000. Specifying the - sign is optional.

For example, to display the -359 error message, you can enter either of the following:finderr -359

or, equivalently:finderr 359

The following example demonstrates how to specify a list of error messages. The example also pipes the output to the UNIX more command to control the display. You can also direct the output to another le so that you can save or print the error messages:finderr 233 107 113 134 143 144 154 | more

A few messages have positive numbers. These messages are used solely within the application tools. In the unlikely event that you want to display them, you must precede the message number with the + sign. The messages numbered -1 to -100 can be platform-dependent. If the message text for a message in this range does not apply to your platform, check the operating system documentation for the precise meaning of the message number.

Introduction 19

Related Reading

Related ReadingThe following Informix database server publications provide additional information about the topics that this manual discusses:s

Informix database servers and the SQL language are described in separate manuals, including Informix Guide to SQL: Tutorial, Informix Guide to SQL: Syntax, and Informix Guide to SQL: Reference. Information about setting up Informix database servers is provided in the Administrators Guide for your Informix database server.

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Informix Press, in partnership with Prentice Hall, publishes books about Informix products. Authors include experts from Informix user groups, employees, consultants, and customers. Recent titles about INFORMIX-4GL include:s s

Advanced INFORMIX-4GL Programming, by Art Taylor, 1995. Programming Informix SQL/4GL: A Step-by-Step Approach, by Cathy Kipp, 1998. Informix Basics, by Glenn Miller, 1998.

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You can access Informix Press on the Web at the following URL:http://www.informix.com/ipress

Informix Developer NetworkInformix maintains the Informix Developer Network (IDN) as a resource by which developers of Informix-based applications can exchange information with their peers and with Informix experts. You can access the Informix Developer Network on the Web at the following URL:http://www.informix.com/idn

20


Informix Welcomes Your Comments

Informix Welcomes Your CommentsLet us know what you like or dislike about our manuals. To help us with future versions of our manuals, we want to know about any corrections or clarications that you would nd useful. Include the following information:s s s

The name and version of the manual that you are using Any comments that you have about the manual Your name, address, and phone number

Write to us at the following address: Informix Software, Inc. Technical Publications Department 4100 Bohannon Drive Menlo Park, CA 94025 If you prefer to send electronic mail, our address is:[email protected]

We appreciate your suggestions. Important: The doc alias is monitored only by the Informix departments that create and maintain manuals and on-line documentation les. It is not an appropriate channel for technical support issues, sales inquiries, or questions about the availability of Informix products.

Introduction 21

Chapter

Compiling INFORMIX-4GL Source FilesIn This Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 1-3 1-4 1-4 1-4 1-5 1-6 1-6 1-7 1-9 1-9 1-10 1-15 1-20 1-27 1-27 1-28 1-28 1-29 1-30 1-33 1-33 1-35 1-35 1-35 1-36 1-40 1-42 1-46 1-47

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Two Implementations of INFORMIX-4GL . . . . . . Runtime and Compile-Time Requirements . . . . Differences Between the C Compiler and RDS Versions Differences in the Programmers Environment . Differences in Commands . . . . . . . . Differences in Filename Extensions . . . . .

The C Compiler Version . . . . . . . . . . . . . . . The Five-Phase 4GL Compilation Process. . . . . . . . The Programmers Environment . . . . . . . . . . . The INFORMIX-4GL Menu . . . . . . . . . . . The MODULE Design Menu . . . . . . . . . . The FORM Design Menu . . . . . . . . . . . . The PROGRAM Design Menu . . . . . . . . . . The QUERY LANGUAGE Menu . . . . . . . . . Creating Programs in the Programmers Environment . . . Creating a New Source Module . . . . . . . . . . Revising an Existing Module . . . . . . . . . . . Compiling a Source Module . . . . . . . . . . . Linking Program Modules . . . . . . . . . . . Executing a Compiled Program . . . . . . . . . . Creating Programs at the Command Line. . . . . . . . Creating or Modifying a 4GL Source File . . . . . . Compiling a 4GL Module . . . . . . . . . . . . Compiling and Linking Multiple Source Files . . . . . Using the c4gl Script for Compilation . . . . . . . . The -globcurs and -localcurs Options . . . . . . . . Shared Libraries . . . . . . . . . . . . . . . Invoking a Compiled 4GL Program at the Command Line Program Filename Extensions . . . . . . . . . . .

The Rapid Development System . . . . . . . . . The Programmers Environment . . . . . . . . The INFORMIX-4GL Menu . . . . . . . . The MODULE Design Menu . . . . . . . . The FORM Design Menu . . . . . . . . . The PROGRAM Design Menu . . . . . . . The QUERY LANGUAGE Menu . . . . . . Creating Programs in the Programmers Environment Creating a New Source Module . . . . . . . Revising an Existing Module . . . . . . . . Compiling a Source Module . . . . . . . . Combining Program Modules . . . . . . . Executing a Compiled RDS Program . . . . . Invoking the Debugger . . . . . . . . . . Creating Programs at the Command Line . . . . . Creating or Modifying a 4GL Source File . . . . Compiling an RDS Source File . . . . . . . Concatenating Multi-Module Programs . . . . Running RDS Programs . . . . . . . . . Running Multi-Module Programs . . . . . . Running Programs with the Interactive Debugger RDS Programs That Call C Functions . . . . . Editing the fgiusr.c File . . . . . . . . . . Creating a Customized Runner . . . . . . . Running Programs That Call C Functions . . . Program Filename Extensions . . . . . . . . .

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1-49 1-49 1-49 1-50 1-56 1-61 1-68 1-69 1-69 1-70 1-71 1-72 1-74 1-75 1-75 1-77 1-77 1-79 1-80 1-82 1-82 1-83 1-84 1-87 1-90 1-90

1-2


In This ChapterThis chapter describes how to create INFORMIX-4GL source-code modules, and how to produce executable 4GL programs from these modules, both at the operating system prompt and in the Programmers Environment. Procedures to do this are shown for the INFORMIX-4GL C Compiler, as well as for the INFORMIX-4GL Rapid Development System. These two implementations of 4GL differ in how they process 4GL source-code modules. This chapter begins by identifying differences between the two implementations of 4GL. It then goes on to describe each implementation of 4GL. Except as otherwise noted, the other chapters and appendixes of this manual describe features that are identical in both the C Compiler and the Rapid Development System implementations of 4GL.

Two Implementations of INFORMIX-4GLTo write a 4GL program, you must rst create an ASCII le of 4GL statements that perform logical tasks to support your application. This chapter explains the procedures by which you can transform one or more source-code les of 4GL statements into an executable 4GL program. Informix offers two implementations of the 4GL application development language:s

The INFORMIX-4GL C Compiler, whose preprocessor generates extended ESQL/C source code. This code is further processed in several steps to produce C source code, which is compiled and linked as object code in an executable command le. The INFORMIX-4GL Rapid Development System (RDS), which uses a compiler to produce pseudo-machine code (called p-code) in a single step. You then invoke a runner to execute the p-code version of your application. For more details, see Compiling and Linking Multiple Source Files on page 1-35.Compiling INFORMIX-4GL Source Files 1-3

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Runtime and Compile-Time Requirements

Important: This version of the runner or Debugger cannot interpret programs compiled to p-code by releases of 4GL earlier than Version 7.30. You must rst recompile your source les and form specications. Similarly, releases of the 4GL runner or Debugger earlier than Version 7.30 cannot interpret p-code that this release produces.

Runtime and Compile-Time RequirementsYou must set the UNIX environment variable that species the pathname to the function libraries that 4GL requires to compile and execute the 4GL program. If you are using the Bourne or Korn shell, specify the following:LD_LIBRARY_PATH=$INFORMIXDIR/lib:$INFORMIXDIR/lib/esql:$INFORMIXDIR/lib/ tools export LD_LIBRARY_PATH

If you are using the C shell, use these equivalent commands:setenv LD_LIBRARY_PATH $INFORMIXDIR/lib:$INFORMIXDIR/lib/esql:$INFORMIXDIR/lib/tools

Important: On some platforms, LD_LIBRARY_PATH has a different name. Please see the machine-specic notes that are provided with 4GL for the name of this environment variable on your platform. Earlier releases of 4GL before Version 7.31 required a different setting.

Differences Between the C Compiler and RDS VersionsBoth implementations of 4GL use the same 4GL statements and nearly identical Programmers Environments. Because they use different methods to compile 4GL source les into executable programs, however, there are a few differences in the user interfaces, as described in sections that follow.

Differences in the Programmers EnvironmentThe Programmers Environment is a system of menus that supports the various steps in the process of developing 4GL application programs. The Drop option on the PROGRAM design menu of the C Compiler is called Undene in the Rapid Development System implementation.

1-4


Differences Between the C Compiler and RDS Versions

The New and Modify options of the PROGRAM design menu display a different screen form in the two implementations. Both of these screen forms are illustrated later in this chapter. The Rapid Development System includes a Debug option on its MODULE design menu and PROGRAM design menu. This option does not appear in the C Compiler. (The Debugger is based on p-code, so it can execute only 4GL programs and modules that have been compiled by the Rapid Development System.) The INFORMIX-4GL Interactive Debugger is available as a separate product.

Differences in CommandsThe commands you use to enter the Programmers Environments, compile and execute 4GL programs, and build or restore the stores7 demonstration database vary between implementations of 4GL.C Compiler i4gl c4gl sle.4gl xle.4ge i4gldemo RDS r4gl fglpc sle fglgo xle r4gldemo Effect of Command Enter Programmers Environment Compile 4GL source le sle.4gl Execute compiled 4GL program xle Create the demonstration database

The C Compiler requires no equivalent command to the fglgo command, because its compiled object les are executable without a runner. The Rapid Development System also contains a command-le script to compile and execute 4GL programs that call C functions or INFORMIX-ESQL/C functions, as described in RDS Programs That Call C Functions on page 1-83.

Compiling INFORMIX-4GL Source Files

1-5

The C Compiler Version

Differences in Filename ExtensionsThe differences in lename extensions are as follows.C Compiler .o .4ge RDS .4go .4gi Signicance of Extension Compiled 4GL source-code module Executable (runable) 4GL program le

The backup le extensions .4bo and .4be for compiled modules and programs have the same names in both implementations. These les are not interchangeable between the two 4GL implementations, however, because object code produced by a C compiler is different from p-code. Other lename extensions that are the same in both the C Compiler and the Rapid Development System designate interchangeable les, if you use both implementations of 4GL to process the same 4GL source-code module.

The C Compiler VersionThis section describes the following aspects of the C compiler version of 4GL:s s

The ve steps of the compilation process All the menu options and screen form elds of the Programmers Environment The steps for compiling and executing 4GL programs from the Programmers Environment The equivalent command-line syntax for compiling and executing 4GL programs The lename extensions of 4GL source-code, object, error, and backup les

s

s

s

1-6


The Five-Phase 4GL Compilation Process

The Five-Phase 4GL Compilation ProcessVersions of 4GL earlier than 6.0 were built on ESQL/C. To make 4GL more independent of ESQL/C, the compilation sequence requires one or more extra processes. Figure 1-1 on page 1-8 shows the ve compilation phases in INFORMIX-4GL 6.0 and subsequent release versions. The ve phases are as follows:1.

The i4glc1 preprocessor converts a 4GL source le with .4gl extension into a le with .4ec extension. It parses the 4GL language and generates C code to handle function and report denitions, computations, and function calls. It generates extended ESQL/C statements to handle forms, menus, input statements, and display statements, and pure ESQL/C to handle SQL statements and declarations of variables. i4glc1 is similar to Version 4.12 and earlier fglc, except that i4glc1 generates a .4ec le instead of a .ec le. The i4glc2 preprocessor translates the extended form, menu, input, and display statements to pure C code but leaves variable declarations and SQL statements unchanged. i4glc2 accepts a .4ec le generated by i4glc1 as input and produces a .ec le containing pure ESQL/C code.

2.


1-7

The Five-Phase 4GL Compilation Process

3.

The i4glc3 preprocessor is a copy of the ESQL/C compiler. The i4glc3 preprocessor accepts a .ec le (produced by i4glc2 or written as pure ESQL/C code), and produces a .c le. The declarations and the SQL statements are mapped to pure C language code.Figure 1-1 Five-Phase Compilation Process

le.4gl i4glc1

le.ec

le.4ec

i4glc2 i4glc3

le.c CC i4glc4 4. le.c

le.o or le.4ge

The i4glc4 preprocessor converts C code, which may contain nonASCII characters in variable names, into de-internationalized names. This step ensures that dening a record like table.* or a eld like table.column does not produce C code that contains non-ASCII character in identiers (because very few C compilers accept nonASCII characters in the names of variables). Informix uses the system C compiler to convert the C code generated by i4glc3 or i4glc4 into object les (a le with .o extension) and executable programs (a le with .4ge extension).

5.

1-8


The Programmers Environment

The Programmers EnvironmentThe C Compiler provides a series of nested menus, called the Programmers Environment. These menus support the steps of 4GL program development and keep track of the components of your application. You can invoke the Programmers Environment by entering i4gl at the system prompt.

The INFORMIX-4GL MenuThe i4gl command briey displays the INFORMIX-4GL banner. Then a menu appears, called the INFORMIX-4GL menu.INFORMIX-4GL: Module Form Program Query-language Exit Create, modify, or run individual 4GL program modules. ------------------------------------------Press CTRL-W for Help------

This is the highest menu, from which you can reach any other menu of the Programmers Environment. You have ve options:s s s s

Module. Work on a 4GL program module. Form. Work on a screen form. Program. Specify components of a multi-module program. Query-language. Use an SQL interactive interface, if you have either INFORMIX-SQL or DB-Access installed on your system. (See the documentation of these Informix products for details of their use.) Exit. Terminate i4gl and return to the operating system.

s

The rst three options display new menus that are described in the pages that follow. (You can also press CONTROL-W at any menu to display an on-line help message that describes your options.) As at any 4GL menu, you can choose an option in either of two ways:s s

By typing the rst letter of the option By using the SPACEBAR or arrow keys to move the highlight to the option that you choose, and then pressing RETURNCompiling INFORMIX-4GL Source Files 1-9


The MODULE Design MenuYou can press RETURN or type m or M to choose the Module option of the INFORMIX-4GL menu. This displays a new menu, called the MODULE design menu. Use this menu to work on an individual 4GL source-code module.MODULE: Modify New Compile Program_Compile Change an existing 4GL program module. Run Exit

-------------------------------------------Press CTRL-W for Help------

Use this menu to create and compile source-code modules of a 4GL application. (For information on creating and compiling 4GL screen forms, see The FORM Design Menu on page 1-15. For details of how to create and compile help messages, see the mkmessage utility in Appendix B, INFORMIX-4GL Utility Programs.) The MODULE design menu supports the following options:s s s s s

Modify. Change an existing 4GL source-code module. New. Create a new source-code module. Compile. Compile a source-code module. Program_Compile. Compile a 4GL application program. Run. Execute a compiled 4GL program module or a multi-module application program. Exit. Return to the INFORMIX-4GL menu.

s

Within the Programmers Environment, the Exit option returns control to the higher menu from which you accessed the current menu (or, when you choose Exit from the INFORMIX-4GL menu, terminates the 4GL session and returns to the system prompt).

1-10



The Modify OptionChoose this option to edit an existing 4GL source-code module. If you choose this option, 4GL requests the name of the 4GL source-code le to be modied and then prompts you to specify a text editor. If you have designated a default editor with the DBEDIT environment variable (which is described in Appendix D) or if you specied an editor at the Programmers Environment previously in this session, 4GL invokes that editor. The .4gl source le whose lename you specied is the current le. When you leave the editor, 4GL displays the MODIFY MODULE menu, with the Compile option highlighted.MODIFY MODULE: Compile Save-and-exit Compile the 4GL module specification. Discard-and-exit


If you press RETURN or type c or C to choose the Compile option, 4GL displays the COMPILE MODULE menu:COMPILE MODULE: Object Runable Exit Create object file only; no linking to occur. -------------------------------------------Press CTRL-W for Help------

The Object option creates a compiled le with the .o extension but makes no attempt to link the le with other les.


1-11


The Runable option creates a compiled le with the .4ge extension. 4GL assumes that the current module is a complete 4GL program, and that no other module needs to be linked to it. Choose the Runable option if the current program module is a stand-alone 4GL program. If this is not the case (that is, if the le is one of several 4GL source-code modules within a multimodule program), then you should use the Object option instead, and you must use the PROGRAM design menu to specify all the component modules. After you choose Object or Runable, a message near the bottom of the screen will advise you if 4GL issues a compile-time warning or error. If there are warnings (but no errors), an object le is produced. Choose the Exit option of the next menu, and then Save-and-exit at the MODIFY MODULE menu, if you wish to save the executable le without reading the warnings. Alternatively, you can examine the warning messages by choosing Correct at the next menu. When you nish editing the .err le that contains the warnings, you must choose Compile again from the MODIFY MODULE menu, because the Correct option deletes the executable le. If there are compilation errors, the following menu appears.COMPILE MODULE: Correct Exit Correct errors in the 4GL module. -------------------------------------------Press CTRL-W for Help------

If you choose to correct the errors, an editing session begins on a copy of your source module with embedded error messages. You do not need to delete the error messages because 4GL does this for you. Correct your source le, save your changes, and exit from the editor. The MODIFY MODULE menu reappears, prompting you to recompile, save, or discard your changes without compiling. If you choose not to correct the errors, you are prompted to Save or Discard the le.

1-12



If there are no compilation errors, the MODIFY MODULE menu appears with the Save-and-Exit option highlighted. Choose this option to save the current source-code module as a le with extension .4gl, and create an object le with the same lename, but with the extension .o. If you specied Runable when you compiled, the executable version is saved with the extension .4ge. The Discard-and-Exit option discards any changes that were made to your le after you chose the Modify option.

The New OptionChoose this option to create a new 4GL source-code module.MODULE: Modify New Compile Program_Compile Create a new 4GL program module. Run Exit


This option resembles the Modify option, but NEW MODULE is the menu title, and you must enter a new module name, rather than choose it from a list. The lename of the module must be unique among source-code modules of the same 4GL program, and can include up to 10 characters, not including the .4gl le extension. If you have not designated an editor previously in this session or with DBEDIT, you are prompted for an editor. Then an editing session begins.


1-13


The Compile OptionThe Compile option enables you to compile an individual 4GL source-code module.MODULE: Modify New Compile Program_Compile Compile an existing 4GL program module. Run Exit


After you specify the name of a 4GL source-code module to compile, the screen displays the COMPILE MODULE menu. Its Object, Runable, and Exit options were described earlier in the discussion of the Modify option.

The Program_Compile OptionThe Program_Compile option of the MODULE design menu is the same as the Compile option of the PROGRAM design menu. This option can compile and link modules, as described in the program specication database, taking into account the time when the modules were last updated. This option is useful after you modify a single module of a complex program, and need to test it by compiling and linking it with the other modules.

The Run OptionChoose the Run option to begin execution of a compiled 4GL program.MODULE: Modify New Compile Program_Compile Run Exit Execute an existing 4GL program module or application program. -------------------------------------------Press CTRL-W for Help------

1-14



The RUN PROGRAM screen lists compiled modules and programs, with the highlight on the module corresponding to the current le, if any has been specied. Only compiled programs with extension .4ge are listed. If you compile a program outside the Programmers Environment and you want it to appear in this list, give it the extension .4ge. If no compiled programs exist, 4GL displays an error message and returns to the MODULE design menu. You can exit to the maine INFORMIX-4GL menu, and select the Program option to create the database.

The Exit OptionChoose this option to exit from the MODULE design menu and display the INFORMIX-4GL menu.MODULE: Modify New Compile Program_Compile Returns to the INFORMIX-4GL menu. Run Exit


The FORM Design MenuYou can type f or F at the INFORMIX-4GL menu to choose the Form option. This option displays a menu, called the FORM design menu.FORM: Modify Generate New Compile Exit Change an existing form specification. -------------------------------------------Press CTRL-W for Help------


1-15


You can use this menu to create, modify, and compile screen form specications. These dene visual displays that 4GL applications can use to query and modify the information in a database. 4GL form specication les are ASCII les that are described in Chapter 6, Screen Forms. The FORM design menu supports the following options:s s s s s

Modify. Change an existing 4GL screen form specication. Generate. Create a default 4GL screen form specication. New. Create a new 4GL screen form specication. Compile. Compile an existing 4GL screen form specication. Exit. Return to the INFORMIX-4GL menu.

Readers familiar with INFORMIX-SQL may notice that this resembles the menu displayed by the Form option of the INFORMIX-SQL main menu.

The Modify OptionThe Modify option of the FORM design menu enables you to edit an existing form specication le. It resembles the Modify option in the MODULE design menu, because both options are used to edit program modules.FORM: Modify Generate New Compile Exit Change an existing form specification. -------------------------------------------Press CTRL-W for Help------

If you choose this option, you are prompted to choose the name of a form specication le to modify. Source les created at the FORM design menu have the le extension .per. (If you use a text editor outside of the Programmers Environment to create form specication les, you must give them the extension .per before you can compile them with the FORM4GL screen form facility.)

1-16



If you have not already designated a text editor in this 4GL session or with DBEDIT, you are prompted for the name of an editor. Then an editing session begins, with the form specication source-code le that you specied as the current le. When you leave the editor, 4GL displays the MODIFY FORM menu with the Compile option highlighted. Now you can press RETURN to compile the revised form specication le.MODIFY FORM: Compile Save-and-exit Compile the form specification. Discard-and-exit


If there are compilation errors, 4GL displays the COMPILE FORM menu.COMPILE FORM: Correct Exit Correct errors in the form specification. -------------------------------------------Press CTRL-W for Help------

Press RETURN to choose Correct as your option. An editing session begins on a copy of the current form, with diagnostic error messages embedded where the compiler detected syntax errors. 4GL automatically deletes these messages when you save the le and exit from the editor. After you have corrected the errors, the MODIFY FORM menu appears again, with the Compile option highlighted. Press RETURN to recompile. Repeat these steps until the compiler reports no errors. (If you choose Exit instead of Correct, you are prompted to Save or Discard the le.) If there are no compilation errors, you are prompted to save the modied form specication le and the compiled form, or to discard the changes. (Discarding the changes restores the version of your form specications from before you chose the Modify option.)


1-17


The Generate OptionYou can type g or G to choose the Generate option. This option creates a simple default screen form that you can use directly in your program, or that you can later edit by choosing the Modify option.FORM: Modify Generate New Compile Exit Generate and compile a default form specification. -------------------------------------------Press CTRL-W for Help------

When you choose this option, 4GL prompts you to select a database, to choose a lename for the form specication, and to identify the tables that the form will access. After you provide this information, 4GL creates and compiles a form specication le. (This is equivalent to running the -d (default) option of the form4gl command, as described in Compiling a Form at the Command Line on page 6-87.)

The New OptionThe New option of the FORM design menu enables you to create a new screen form specication.FORM: Modify Generate New Compile Create a new form specification. Exit


After prompting you for the name of your form specication le, 4GL places you in the editor where you can create a form specication le. When you leave the editor, 4GL transfers you to the NEW FORM menu that is like the MODIFY FORM menu. You can compile your form and correct it in the same way.1-18 IBM Informix 4GL Reference Manual


The Compile OptionThe Compile option enables you to compile an existing form specication le without going through the Modify option.FORM: Modify Generate New Compile Exit Compile an existing form specification. -------------------------------------------Press CTRL-W for Help------

4GL compiles the form specication le whose name you specify. If the compilation fails, 4GL displays the COMPILE FORM menu with the Correct

option highlighted.

The Exit OptionThe Exit option restores the INFORMIX-4GL menu.FORM: Modify Generate New Compile Returns to the INFORMIX-4GL menu. Exit



1-19


The PROGRAM Design MenuA 4GL program can be a single source-code module that you create and compile at the MODULE design menu. For applications of greater complexity, however, it is often easier to create separate 4GL modules. The INFORMIX-4GL menu includes the Program option to create multi-module programs. If you choose this option, 4GL searches your DBPATH directories for the program design database, which stores the names of the objects that are used to create programs and their build dependencies. (For more information on the DBPATH environment variable, see Appendix D.) This program design database describes the component modules and function libraries of your 4GL program. By default, its name is syspgm4gl, but you can use the PROGRAM_DESIGN_DBS environment variable to specify some other name. (For more information on the PROGRAM_DESIGN_DBS environment variable, see Appendix D.) If 4GL cannot nd this database, you are asked if you want one created. If you enter y in response, 4GL creates the syspgm4gl database, grants CONNECT privileges to PUBLIC, and displays the PROGRAM design menu. As database administrator of syspgm4gl, you can later restrict the access of other users. If syspgm4gl already exists, the PROGRAM design menu appears.PROGRAM: Modify New Compile Planned_Compile Run Drop Exit Change the compilation definition of a 4GL application program. -------------------------------------------Press CTRL-W for Help------

You can use this menu to create or modify a multi-module 4GL program specication, to compile and link a program, or to execute a program.

1-20



The PROGRAM design menu supports the following options:s s s s

Modify. Change an existing program specication. New. Create a new program specication. Compile. Compile an existing program. Planned_Compile. List the steps necessary to compile and link an existing program. Run. Execute an existing program. Drop. Delete an existing program specication. Exit. Return to the INFORMIX-4GL menu.

s s s

You must rst use the MODULE design menu and the FORM design menu to enter and edit the 4GL statements within the component source-code modules of a 4GL program. Then you can use the PROGRAM design menu to identify which modules are part of the same application program, and to link all the modules as an executable command le.

The Modify OptionThe Modify option enables you to modify the specication of an existing 4GL program. (This option is not valid unless at least one program has already been specied. If none has, you can create a program specication by choosing the New option from the same menu.)4GL prompts you for the name of the program specication to be modied. It

then displays a menu and form that you can use to update the information in the program specication database, as shown in Figure 1-2.


1-21


Figure 1-2 Example of a Program Specication EntryMODIFY PROGRAM: 4GL Other Edit the 4GL sources list. Libraries Compile_Options Rename Exit

-------------------------------------------Press CTRL-W for Help-----Program [myprog ] 4gl Source [main [funct [rept [ [ 4gl Source Path [/u/john/appl/4GL [/u/john/appl/4GL [/u/john/appl/4GL [ [ Ext [c [ [ [ Other Source Path [/u/john/appl/C [ [ [ Compile Options [ [ ] ]

] ] ] ] ]

] ] ] ] ]

Other Source [cfunc ] [ ] [ ] [ ] Libraries [m [

] ] ] ] ] ]

] ] ] ]

The name of the program appears in the Program eld. In Figure 1-2 the name is myprog. You can change this name by choosing the Rename option. 4GL assigns the program name, with the extension .4ge, to the executable program produced by compiling and linking all the source les and libraries. (Compiling and linking occurs when you choose the Compile_Options option, as described later in this section.) In this example, the resulting executable program would have the name myprog.4ge. Use the 4GL option to update the entries for the 4gl Source elds and the 4gl Source Path elds on the form. The ve rows of elds under these labels form a screen array. When you choose the 4GL option, 4GL executes an INPUT ARRAY statement so you can move and scroll through the array. See the INPUT ARRAY statement in Chapter 4, INFORMIX-4GL Statements, for information about how to use your function keys to scroll, delete rows, and insert new rows. (You cannot redene the function keys, however, as you can with a 4GL program.)

1-22



The 4GL source program that appears in Figure 1-2 on page 1-22 contains three modules:s s s

One module contains the main program (main.4gl). One module contains functions (funct.4gl). One module contains REPORT statements (rept.4gl).

Each module is located in the directory /u/john/appl/4GL. If your program includes a module containing only global variables (for example, global.4gl), you must also list that module in this section. Use the Other option to include non-4GL source modules or object-code modules in your program. Enter this information into the three-column screen array with the headings Other Source, Ext, and Other Source Path. Enter the lename and location of each non-4GL source-code or object-code module in these elds. Enter the name of the module in the Other Source eld, the lename extension of the module (for example, ec for an INFORMIX-ESQL/C module, or c for a C module) in the Ext eld, and the full directory path of the module in the Other Source Path eld. The example in Figure 1-2 includes a le containing C function source-code (cfunc.c) located in /u/john/appl/C. You can list up to 100 les in this array. The Libraries option enables you to indicate the names of up to ten special libraries to link with your program. 4GL calls the C compiler to do the linking and adds the appropriate -l prex, so you should enter only what follows the prex. The example displayed in Figure 1-2 calls only the standard C math library. Use the Compile_Options option to indicate up to ten C compiler options. Enter this information in the Compile Options eld. Do not, however, specify the -e or -a options of c4gl in this eld, because they will cause the compilation to fail. (See Creating Programs at the Command Line on page 1-33 for more information about the options of the c4gl command.) The Exit option exits from the MODIFY PROGRAM menu and displays the PROGRAM design menu.


1-23


The New OptionUse the New option on the PROGRAM design menu to create a new specication of the program modules and libraries that make up an application program. You can also specify any necessary compiler or loader options.PROGRAM: Modify New Compile Planned_Compile Run Drop Exit Add the compilation definition of a 4GL application program. -------------------------------------------Press CTRL-W for Help------

The submenu screen forms displayed by the New and the Modify options of the PROGRAM design menu are identical, except that you must rst supply a name for your program when you choose the New option. (4GL displays a blank form in the NEW PROGRAM menu.) The NEW PROGRAM menu has the same options as the MODIFY PROGRAM menu, as illustrated earlier.

The Compile OptionThe Compile option performs the compilation and linking described in the program specication database, taking into account the time when each le was last updated. It compiles only those les that have not been compiled since they were last modied.PROGRAM: Modify New Compile Planned_Compile Compile a 4GL application program. Run Drop Exit


4GL lists each step of the preprocessing and compilation as it occurs. An

example of these messages appears in the illustration of the Planned_Compile option, next.1-24 IBM Informix 4GL Reference Manual


The Planned_Compile OptionTaking into account the time when the various les in the dependency relationships last changed, the Planned_Compile option prompts for a program name and displays a summary of the steps that will be executed if you choose the Compile option. No compilation actually takes place.PROGRAM: Modify New Compile Planned_Compile Run Drop Exit Show the planned compile actions of a 4GL application program. -------------------------------------------Press CTRL-W for Help-----Compiling INFORMIX-4GL sources: /u/john/appl/4GL/main.4gl /u/john/appl/4GL/funct.4gl /u/john/appl/4GL/rept.4gl Compiling Embedded SQL sources: Compiling with options: Linking with libraries: m Compiling/Linking other sources: /u/john/appl/C/cfunc.c

In this instance, changes were made to all the components of the 4GL program that were listed in Figure 1-2 on page 1-22. This display indicates that no source-code module has been compiled after the program was changed.


1-25


The Run OptionThe Run option of the PROGRAM design menu is the same as the Run option of the MODULE design menu. It displays a list of any compiled programs (les with the extension .4ge) and highlights the current program, if a program has been specied. 4GL then executes the program that you choose.PROGRAM: Modify New Compile Planned_Compile Execute a 4GL application program. Run Drop Exit


The Drop OptionThe Drop option of the PROGRAM design menu prompts you for a program name and removes the compilation and linking denition of that program from the syspgm4gl database. This action removes the denition only. Your program and 4GL modules are not removed.PROGRAM: Modify New Compile Planned_Compile Run Drop Exit Drop the compilation definition of a 4GL application program. -------------------------------------------Press CTRL-W for Help------

The Exit OptionThe Exit option clears the PROGRAM design menu and restores the INFORMIX-4GL menu.

1-26


Creating Programs in the Programmers Environment

The QUERY LANGUAGE MenuThe SQL interactive interface is identical to the interactive SQL interface of INFORMIX-SQL. If you do not have INFORMIX-SQL, 4GL uses the DB-Access utility. The Query-language option is placed at the top-level menu so you can test SQL statements without leaving the 4GL Programmers Environment. You can also use this option to create, execute, and save SQL scripts.

Creating Programs in the Programmers EnvironmentTo invoke the C Compiler version of the Programmers Environment, enter the following command at the system prompt:i4gl

After a sign-on message is displayed, the INFORMIX-4GL menu appears. To create a 4GL application with the C Compiler version of 4GL1. 2. 3. 4.

Create a new source module or revising an existing source module Compile the source module Link the program modules Execute the compiled program

This process is described in the sections that follow.


1-27


Creating a New Source ModuleThis section outlines the procedure for creating a new source module. If your source module already exists, see Revising an Existing Module, next. To create a source module1.

Choose the Module option of the INFORMIX-4GL menu. The MODULE design menu is displayed. If you are creating a new .4gl source module, choose the New option of the MODULE design menu. Enter a name for the new module. The name must begin with a letter and can include letters, numbers, and underscores. No more than 10 characters are allowed in this name, which must be unique among the les in the same directory, and among any other modules of the same program. 4GL attaches the extension .4gl to this lename of your new module.

2. 3.

4.

Press RETURN.

Revising an Existing ModuleIf you are revising an existing 4GL source le, use the following procedure. To modify a source le1.

Choose the Modify option of the MODULE design menu. The screen lists the names of all the .4gl source modules in the current directory and prompts you to choose a source le to edit.

2.

Use the arrow keys to highlight the name of a source module and press RETURN, or enter a lename (with no extension). If you specied the name of an editor with the DBEDIT environment variable, an editing session with that editor begins automatically. Otherwise, the screen prompts you to specify a text editor. Specify a text editor, or press RETURN for vi, the default editor. Now you can begin an editing session by entering 4GL statements.

3.

When you have nished entering or editing your 4GL code, use an appropriate editor command to save your source le and end the text editing session.

1-28



Compiling a Source ModuleThe .4gl source le module that you create or modify is an ASCII le that must be compiled before it can be executed. To compile a module1. 2.

Choose the Compile option from the MODULE design menu. Choose the type of module that you are compiling, either Runable or Object. If the module is a complete 4GL program that requires no other modules, choose Runable. If the module is one module of a multi-module 4GL program, choose Object. This option creates a compiled object le module, with the same lename, but with extension .o. See also the next section, Linking Program Modules.

3.

If the compiler detects errors, no compiled le is created, and you are prompted to x the problem. Choose Correct to resume the previous text editing session, with the same 4GL source code, but with error messages in the le. Edit the le to correct the error, and choose Compile again. If an error message appears, repeat this process until the module compiles without error.

4.

After the module compiles successfully, choose Save-and-exit from the menu to save the compiled program. The MODULE design menu appears again on your screen. If your program requires screen forms, choose Form from the INFORMIX-4GL menu. The FORM design menu appears. For information about designing and creating screen forms, see Chapter 6.

5.

6.

If your program displays help messages, you must create and compile a help le. Use the mkmessage utility to compile the help le. Fo

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IBM Informix 4GL Reference Manual