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COBOL Tutorial

COBOL MESSAGE Clause - Quick Reference

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Overview

The MESSAGE clause is used in COBOL to define message text that can be used for communication, error handling, and user interface purposes. It provides a structured way to manage and maintain message content throughout COBOL applications.

Purpose and Usage

  • Message definition - Define reusable message text
  • Error handling - Provide consistent error messages
  • User communication - Display information to users
  • Maintainability - Centralize message management
  • Internationalization - Support multiple languages

Message Management Concept

Define messages in WORKING-STORAGE SECTION
Reference messages by data item name
Use DISPLAY to show messages to users
Centralize message management
Support multiple languages and formats

The MESSAGE clause provides structured message management in COBOL programs.

Syntax and Usage

The MESSAGE clause is used to define message text in the DATA DIVISION. It provides a structured approach to message management in COBOL programs.

Basic Syntax

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* Basic MESSAGE clause syntax
level-number data-name PIC X(length) VALUE "message text".
 
* Examples
01  ERROR-MESSAGE-001    PIC X(50) VALUE "File not found".
01  SUCCESS-MESSAGE      PIC X(40) VALUE "Operation completed successfully".
01  WARNING-MESSAGE      PIC X(60) VALUE "Warning: Data may be incomplete".
 
* Complete example
WORKING-STORAGE SECTION.
01  MESSAGES.
    05  MSG-FILE-NOT-FOUND    PIC X(50) VALUE "Error: File not found".
    05  MSG-INVALID-INPUT     PIC X(45) VALUE "Error: Invalid input data".
    05  MSG-SUCCESS           PIC X(40) VALUE "Operation completed successfully".
    05  MSG-WARNING           PIC X(60) VALUE "Warning: Please check your input".

Messages are defined using the VALUE clause with PIC X data types.

Complete Example

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* Complete example using MESSAGE clause
       IDENTIFICATION DIVISION.
       PROGRAM-ID. MESSAGE-DEMO.
       
       ENVIRONMENT DIVISION.
       CONFIGURATION SECTION.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  MESSAGE-TABLE.
           05  MSG-ERROR-001    PIC X(50) VALUE "Error: File not found".
           05  MSG-ERROR-002    PIC X(45) VALUE "Error: Invalid input data".
           05  MSG-ERROR-003    PIC X(55) VALUE "Error: Insufficient permissions".
           05  MSG-SUCCESS-001  PIC X(40) VALUE "Operation completed successfully".
           05  MSG-WARNING-001  PIC X(60) VALUE "Warning: Data may be incomplete".
           05  MSG-INFO-001     PIC X(35) VALUE "Processing data...".
       
       01  USER-INPUT          PIC X(20).
       01  FILE-STATUS         PIC XX.
       01  ERROR-CODE          PIC 9(3).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           * Get user input
           DISPLAY MSG-INFO-001
           ACCEPT USER-INPUT
           
           * Validate input
           IF USER-INPUT = SPACES
               DISPLAY MSG-ERROR-002
               STOP RUN
           END-IF
           
           * Process file operation
           PERFORM PROCESS-FILE
           
           * Display success message
           DISPLAY MSG-SUCCESS-001
           STOP RUN.
       
       PROCESS-FILE.
           * Simulate file processing
           IF FILE-STATUS = "35"
               DISPLAY MSG-ERROR-001
               MOVE 1 TO ERROR-CODE
           ELSE IF FILE-STATUS = "37"
               DISPLAY MSG-ERROR-003
               MOVE 3 TO ERROR-CODE
           ELSE
               DISPLAY MSG-WARNING-001
           END-IF.

This example shows how to define and use messages throughout a program.

Error Handling Example

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* Error handling with MESSAGE clause
       IDENTIFICATION DIVISION.
       PROGRAM-ID. ERROR-HANDLER.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  ERROR-MESSAGES.
           05  ERR-FILE-NOT-FOUND    PIC X(50) VALUE "Error: File not found".
           05  ERR-INVALID-DATA      PIC X(45) VALUE "Error: Invalid data format".
           05  ERR-PERMISSION        PIC X(55) VALUE "Error: Insufficient permissions".
           05  ERR-SYSTEM            PIC X(40) VALUE "Error: System error occurred".
       
       01  FILE-STATUS         PIC XX.
       01  DATA-VALIDATION     PIC X(1).
       01  ERROR-TYPE          PIC 9(1).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           * Perform operations with error handling
           PERFORM VALIDATE-DATA
           PERFORM PROCESS-FILE
           PERFORM CHECK-PERMISSIONS
           
           STOP RUN.
       
       VALIDATE-DATA.
           * Validate input data
           IF DATA-VALIDATION = "N"
               DISPLAY ERR-INVALID-DATA
               MOVE 2 TO ERROR-TYPE
           END-IF.
       
       PROCESS-FILE.
           * Process file with error handling
           IF FILE-STATUS = "35"
               DISPLAY ERR-FILE-NOT-FOUND
               MOVE 1 TO ERROR-TYPE
           ELSE IF FILE-STATUS = "37"
               DISPLAY ERR-PERMISSION
               MOVE 3 TO ERROR-TYPE
           ELSE IF FILE-STATUS NOT = "00"
               DISPLAY ERR-SYSTEM
               MOVE 4 TO ERROR-TYPE
           END-IF.

Error handling uses predefined messages for consistent error reporting.

Common Use Cases

The MESSAGE clause is essential in various scenarios where structured message management is critical for user communication and error handling.

User Interface Applications

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* User interface with MESSAGE clause
       IDENTIFICATION DIVISION.
       PROGRAM-ID. USER-INTERFACE.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  UI-MESSAGES.
           05  MSG-WELCOME        PIC X(40) VALUE "Welcome to the application".
           05  MSG-MENU-OPTION-1  PIC X(30) VALUE "1. Process Data".
           05  MSG-MENU-OPTION-2  PIC X(30) VALUE "2. Generate Report".
           05  MSG-MENU-OPTION-3  PIC X(30) VALUE "3. Exit".
           05  MSG-ENTER-CHOICE   PIC X(25) VALUE "Enter your choice: ".
           05  MSG-INVALID-CHOICE PIC X(35) VALUE "Invalid choice. Please try again.".
           05  MSG-PROCESSING     PIC X(25) VALUE "Processing...".
           05  MSG-COMPLETE       PIC X(30) VALUE "Operation completed.".
       
       01  USER-CHOICE           PIC X(1).
       01  PROCESSING-STATUS     PIC X(1).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           * Display welcome message
           DISPLAY MSG-WELCOME
           
           * Display menu
           DISPLAY MSG-MENU-OPTION-1
           DISPLAY MSG-MENU-OPTION-2
           DISPLAY MSG-MENU-OPTION-3
           
           * Get user choice
           DISPLAY MSG-ENTER-CHOICE
           ACCEPT USER-CHOICE
           
           * Process choice
           EVALUATE USER-CHOICE
               WHEN "1"
                   DISPLAY MSG-PROCESSING
                   PERFORM PROCESS-DATA
                   DISPLAY MSG-COMPLETE
               WHEN "2"
                   DISPLAY MSG-PROCESSING
                   PERFORM GENERATE-REPORT
                   DISPLAY MSG-COMPLETE
               WHEN "3"
                   STOP RUN
               WHEN OTHER
                   DISPLAY MSG-INVALID-CHOICE
           END-EVALUATE.
       
       PROCESS-DATA.
           * Process data logic here
           MOVE "Y" TO PROCESSING-STATUS.
       
       GENERATE-REPORT.
           * Generate report logic here
           MOVE "Y" TO PROCESSING-STATUS.

User interface applications use messages for consistent user communication.

Logging and Debugging

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* Logging and debugging with MESSAGE clause
       IDENTIFICATION DIVISION.
       PROGRAM-ID. LOGGING-DEMO.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  LOG-MESSAGES.
           05  LOG-START          PIC X(30) VALUE "Program execution started".
           05  LOG-DATA-LOADED    PIC X(35) VALUE "Data loaded successfully".
           05  LOG-PROCESSING     PIC X(30) VALUE "Processing data...".
           05  LOG-VALIDATION     PIC X(30) VALUE "Data validation completed".
           05  LOG-ERROR          PIC X(25) VALUE "Error occurred: ".
           05  LOG-COMPLETE       PIC X(30) VALUE "Program execution completed".
       
       01  LOG-FILE-NAME         PIC X(20) VALUE "PROGRAM.LOG".
       01  ERROR-DETAILS         PIC X(50).
       01  LOG-ENTRY             PIC X(100).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           * Log program start
           PERFORM WRITE-LOG-ENTRY USING LOG-START
           
           * Load data
           PERFORM LOAD-DATA
           PERFORM WRITE-LOG-ENTRY USING LOG-DATA-LOADED
           
           * Process data
           PERFORM WRITE-LOG-ENTRY USING LOG-PROCESSING
           PERFORM PROCESS-DATA
           
           * Validate data
           PERFORM WRITE-LOG-ENTRY USING LOG-VALIDATION
           PERFORM VALIDATE-DATA
           
           * Log completion
           PERFORM WRITE-LOG-ENTRY USING LOG-COMPLETE
           STOP RUN.
       
       WRITE-LOG-ENTRY USING LOG-TEXT.
           * Write log entry to file
           MOVE FUNCTION CURRENT-DATE TO LOG-ENTRY(1:8)
           MOVE " - " TO LOG-ENTRY(9:3)
           MOVE LOG-TEXT TO LOG-ENTRY(12:50)
           * Write LOG-ENTRY to log file here.
       
       LOAD-DATA.
           * Load data logic here.
       
       PROCESS-DATA.
           * Process data logic here.
       
       VALIDATE-DATA.
           * Validate data logic here.

Logging and debugging use messages for consistent log entries.

Internationalization

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* Internationalization with MESSAGE clause
       IDENTIFICATION DIVISION.
       PROGRAM-ID. I18N-DEMO.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  LANGUAGE-SETTING     PIC X(2) VALUE "EN".
       01  ENGLISH-MESSAGES.
           05  EN-HELLO         PIC X(20) VALUE "Hello, World!".
           05  EN-GOODBYE       PIC X(20) VALUE "Goodbye!".
           05  EN-ERROR         PIC X(30) VALUE "An error occurred.".
       
       01  SPANISH-MESSAGES.
           05  ES-HELLO         PIC X(20) VALUE "¡Hola, Mundo!".
           05  ES-GOODBYE       PIC X(20) VALUE "¡Adiós!".
           05  ES-ERROR         PIC X(30) VALUE "Ocurrió un error.".
       
       01  FRENCH-MESSAGES.
           05  FR-HELLO         PIC X(20) VALUE "Bonjour, Monde!".
           05  FR-GOODBYE       PIC X(20) VALUE "Au revoir!".
           05  FR-ERROR         PIC X(30) VALUE "Une erreur s'est produite.".
       
       01  CURRENT-MESSAGE      PIC X(30).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           * Display message based on language setting
           PERFORM DISPLAY-MESSAGE USING "HELLO"
           PERFORM DISPLAY-MESSAGE USING "GOODBYE"
           PERFORM DISPLAY-MESSAGE USING "ERROR"
           
           STOP RUN.
       
       DISPLAY-MESSAGE USING MESSAGE-TYPE.
           * Select message based on language and type
           EVALUATE LANGUAGE-SETTING
               WHEN "EN"
                   EVALUATE MESSAGE-TYPE
                       WHEN "HELLO"
                           MOVE EN-HELLO TO CURRENT-MESSAGE
                       WHEN "GOODBYE"
                           MOVE EN-GOODBYE TO CURRENT-MESSAGE
                       WHEN "ERROR"
                           MOVE EN-ERROR TO CURRENT-MESSAGE
                   END-EVALUATE
               WHEN "ES"
                   EVALUATE MESSAGE-TYPE
                       WHEN "HELLO"
                           MOVE ES-HELLO TO CURRENT-MESSAGE
                       WHEN "GOODBYE"
                           MOVE ES-GOODBYE TO CURRENT-MESSAGE
                       WHEN "ERROR"
                           MOVE ES-ERROR TO CURRENT-MESSAGE
                   END-EVALUATE
               WHEN "FR"
                   EVALUATE MESSAGE-TYPE
                       WHEN "HELLO"
                           MOVE FR-HELLO TO CURRENT-MESSAGE
                       WHEN "GOODBYE"
                           MOVE FR-GOODBYE TO CURRENT-MESSAGE
                       WHEN "ERROR"
                           MOVE FR-ERROR TO CURRENT-MESSAGE
                   END-EVALUATE
           END-EVALUATE
           
           DISPLAY CURRENT-MESSAGE.

Internationalization uses message sets for different languages.

Best Practices and Tips

Following these best practices ensures effective use of the MESSAGE clause in COBOL applications.

MESSAGE Clause Best Practices

  • Use descriptive names - Name message data items clearly and consistently
  • Group related messages - Organize messages by type or function
  • Include message codes - Add error codes for easier maintenance
  • Use consistent formatting - Maintain consistent message style and length
  • Plan for internationalization - Consider multiple language support
  • Document message usage - Document when and how messages are used

Message Organization Patterns

PatternDescriptionExample
By TypeGroup by message typeERROR-MESSAGES, INFO-MESSAGES
By FunctionGroup by program functionFILE-MESSAGES, VALIDATION-MESSAGES
By LanguageGroup by languageENGLISH-MESSAGES, SPANISH-MESSAGES
By ModuleGroup by program moduleMAIN-MESSAGES, UTIL-MESSAGES
By SeverityGroup by error severityFATAL-MESSAGES, WARNING-MESSAGES

Performance Considerations

  • Memory usage - Messages consume memory based on their length
  • Initialization overhead - Large message tables may impact startup time
  • String operations - Message manipulation may affect performance
  • I/O operations - Displaying messages involves I/O overhead
  • Maintenance - Large message sets require careful maintenance
  • Testing - Test message display with various scenarios

When to Use MESSAGE Clause

Use CaseMESSAGE SuitabilityReasoning
Error handlingExcellentProvides consistent error messaging
User interfacesExcellentCentralizes user communication
LoggingGoodProvides structured log messages
InternationalizationGoodSupports multiple languages
Data processingPoorNot designed for data manipulation

MESSAGE Clause Quick Reference

UsageSyntaxExample
Basic message01 data-name PIC X(length) VALUE "text"01 MSG-ERROR PIC X(30) VALUE "Error occurred"
Message group01 group-name. 05 msg1 PIC X(n) VALUE "text"01 MESSAGES. 05 MSG-1 PIC X(20) VALUE "Hello"
Display messageDISPLAY message-nameDISPLAY MSG-ERROR
Error message01 error-msg PIC X(n) VALUE "Error: description"01 ERR-FILE PIC X(40) VALUE "Error: File not found"
Success message01 success-msg PIC X(n) VALUE "Success message"01 MSG-SUCCESS PIC X(35) VALUE "Operation completed"

Test Your Knowledge

1. What is the primary purpose of the MESSAGE clause in COBOL?

  • To perform arithmetic operations
  • To define message text and handle communication
  • To control file operations
  • To manage memory allocation

2. Where is the MESSAGE clause typically defined in a COBOL program?

  • In the PROCEDURE DIVISION
  • In the DATA DIVISION under WORKING-STORAGE SECTION
  • In the ENVIRONMENT DIVISION
  • In the IDENTIFICATION DIVISION

3. How is the MESSAGE clause typically used in COBOL programs?

  • For arithmetic calculations
  • For defining error messages and user communication
  • For file I/O operations
  • For data validation

4. Which of the following is a common use case for the MESSAGE clause?

  • Data processing
  • Error handling and user feedback
  • File operations
  • Mathematical calculations

5. How do you reference a message defined with the MESSAGE clause?

  • By using the message text directly
  • By referencing the data item name
  • By calling a system function
  • By using a special register

Frequently Asked Questions

Related Concepts

DISPLAY Statement

Understanding the DISPLAY statement for output.

Error Handling

Complete guide to error handling in COBOL.

User Interface Design

Designing user interfaces in COBOL.

Internationalization

Supporting multiple languages in COBOL.

Data Validation

Validating data with proper messaging.

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