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COBOL Tutorial

COBOL CONSOLE - Quick Reference

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Overview

CONSOLE in COBOL refers to a terminal or display device that allows for user interaction and display output. It is used for creating interactive applications where users can see output and potentially provide input through the console interface, enabling user-friendly applications and real-time interaction.

Purpose and Usage

  • User interaction and input/output
  • Interactive applications
  • Real-time feedback
  • Debugging and monitoring
  • User-friendly interfaces

Syntax

CONSOLE operations follow specific syntax patterns in COBOL:

Basic CONSOLE Operations

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* Basic console output
DISPLAY "Hello, World!" UPON CONSOLE.
DISPLAY "Welcome to the application" UPON CONSOLE.
 
* Console input
ACCEPT user-input FROM CONSOLE.
ACCEPT user-choice FROM CONSOLE.
 
* Console with formatting
DISPLAY "Enter your name: " UPON CONSOLE.
ACCEPT user-name FROM CONSOLE.
DISPLAY "Hello, " user-name "!" UPON CONSOLE.
 
* Console with multiple lines
DISPLAY "Menu Options:" UPON CONSOLE.
DISPLAY "1. Add Record" UPON CONSOLE.
DISPLAY "2. View Records" UPON CONSOLE.
DISPLAY "3. Exit" UPON CONSOLE.
DISPLAY "Enter your choice: " UPON CONSOLE.
ACCEPT menu-choice FROM CONSOLE.

CONSOLE is used with DISPLAY and ACCEPT statements for user interaction.

Console with Error Handling

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* Console operations with error handling
PROCEDURE DIVISION.
CONSOLE-INTERACTION.
    * Display welcome message
    DISPLAY "Welcome to the COBOL Console Application" UPON CONSOLE.
    DISPLAY "=====================================" UPON CONSOLE.
    
    * Get user input with validation
    PERFORM get-user-input.
    
    * Process user input
    PERFORM process-user-choice.
    
    STOP RUN.
 
GET-USER-INPUT.
    DISPLAY "Please enter your choice (1-3): " UPON CONSOLE.
    ACCEPT user-choice FROM CONSOLE.
    
    * Validate input
    IF user-choice IS NOT NUMERIC OR
       user-choice < 1 OR user-choice > 3
        DISPLAY "Invalid choice. Please enter 1, 2, or 3." UPON CONSOLE.
        PERFORM get-user-input
    END-IF.
 
PROCESS-USER-CHOICE.
    EVALUATE user-choice
        WHEN 1
            DISPLAY "You selected: Add Record" UPON CONSOLE.
            PERFORM add-record-process
        WHEN 2
            DISPLAY "You selected: View Records" UPON CONSOLE.
            PERFORM view-records-process
        WHEN 3
            DISPLAY "You selected: Exit" UPON CONSOLE.
            PERFORM exit-process
    END-EVALUATE.

Practical Examples

Here are some practical uses of CONSOLE in COBOL:

Interactive Menu System

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* Interactive menu system using console
DATA DIVISION.
WORKING-STORAGE SECTION.
01  menu-choice PIC 9.
01  user-name PIC X(30).
01  user-age PIC 9(3).
01  continue-flag PIC X VALUE "Y".
 
PROCEDURE DIVISION.
MAIN-MENU.
    * Display main menu
    DISPLAY "=== COBOL Console Application ===" UPON CONSOLE.
    DISPLAY "1. User Registration" UPON CONSOLE.
    DISPLAY "2. Data Processing" UPON CONSOLE.
    DISPLAY "3. Report Generation" UPON CONSOLE.
    DISPLAY "4. System Information" UPON CONSOLE.
    DISPLAY "5. Exit" UPON CONSOLE.
    DISPLAY "================================" UPON CONSOLE.
    
    * Get user choice
    DISPLAY "Enter your choice (1-5): " UPON CONSOLE.
    ACCEPT menu-choice FROM CONSOLE.
    
    * Process menu choice
    EVALUATE menu-choice
        WHEN 1
            PERFORM user-registration
        WHEN 2
            PERFORM data-processing
        WHEN 3
            PERFORM report-generation
        WHEN 4
            PERFORM system-information
        WHEN 5
            PERFORM exit-application
        WHEN OTHER
            DISPLAY "Invalid choice. Please try again." UPON CONSOLE.
            PERFORM main-menu
    END-EVALUATE.
    
    * Continue or exit
    IF continue-flag = "Y"
        PERFORM main-menu
    END-IF.
    
    STOP RUN.
 
USER-REGISTRATION.
    DISPLAY "=== User Registration ===" UPON CONSOLE.
    DISPLAY "Enter your name: " UPON CONSOLE.
    ACCEPT user-name FROM CONSOLE.
    
    DISPLAY "Enter your age: " UPON CONSOLE.
    ACCEPT user-age FROM CONSOLE.
    
    DISPLAY "Registration completed!" UPON CONSOLE.
    DISPLAY "Name: " user-name UPON CONSOLE.
    DISPLAY "Age: " user-age UPON CONSOLE.
    
    DISPLAY "Press Enter to continue..." UPON CONSOLE.
    ACCEPT continue-input FROM CONSOLE.
 
DATA-PROCESSING.
    DISPLAY "=== Data Processing ===" UPON CONSOLE.
    DISPLAY "Processing data..." UPON CONSOLE.
    * Data processing logic here
    DISPLAY "Data processing completed!" UPON CONSOLE.
    
    DISPLAY "Press Enter to continue..." UPON CONSOLE.
    ACCEPT continue-input FROM CONSOLE.
 
REPORT-GENERATION.
    DISPLAY "=== Report Generation ===" UPON CONSOLE.
    DISPLAY "Generating report..." UPON CONSOLE.
    * Report generation logic here
    DISPLAY "Report generated successfully!" UPON CONSOLE.
    
    DISPLAY "Press Enter to continue..." UPON CONSOLE.
    ACCEPT continue-input FROM CONSOLE.
 
SYSTEM-INFORMATION.
    DISPLAY "=== System Information ===" UPON CONSOLE.
    DISPLAY "COBOL Console Application" UPON CONSOLE.
    DISPLAY "Version: 1.0" UPON CONSOLE.
    DISPLAY "Date: " FUNCTION CURRENT-DATE UPON CONSOLE.
    
    DISPLAY "Press Enter to continue..." UPON CONSOLE.
    ACCEPT continue-input FROM CONSOLE.
 
EXIT-APPLICATION.
    DISPLAY "Thank you for using the application!" UPON CONSOLE.
    DISPLAY "Goodbye!" UPON CONSOLE.
    MOVE "N" TO continue-flag.

Interactive menu system using console for user interaction.

Data Entry Application

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* Data entry application using console
DATA DIVISION.
WORKING-STORAGE SECTION.
01  customer-data.
    05  customer-id PIC X(10).
    05  customer-name PIC X(50).
    05  customer-email PIC X(100).
    05  customer-phone PIC X(15).
01  record-count PIC 9(4) VALUE 0.
01  continue-entry PIC X VALUE "Y".
 
PROCEDURE DIVISION.
DATA-ENTRY-APPLICATION.
    DISPLAY "=== Customer Data Entry System ===" UPON CONSOLE.
    DISPLAY "This application allows you to enter customer data." UPON CONSOLE.
    DISPLAY "===============================================" UPON CONSOLE.
    
    * Main data entry loop
    PERFORM UNTIL continue-entry = "N"
        PERFORM enter-customer-data
        PERFORM display-customer-data
        PERFORM ask-continue
    END-PERFORM.
    
    * Display summary
    PERFORM display-summary.
    
    STOP RUN.
 
ENTER-CUSTOMER-DATA.
    ADD 1 TO record-count.
    DISPLAY "Entering customer #" record-count UPON CONSOLE.
    DISPLAY "=======================" UPON CONSOLE.
    
    * Get customer ID
    DISPLAY "Enter Customer ID: " UPON CONSOLE.
    ACCEPT customer-id FROM CONSOLE.
    
    * Get customer name
    DISPLAY "Enter Customer Name: " UPON CONSOLE.
    ACCEPT customer-name FROM CONSOLE.
    
    * Get customer email
    DISPLAY "Enter Customer Email: " UPON CONSOLE.
    ACCEPT customer-email FROM CONSOLE.
    
    * Get customer phone
    DISPLAY "Enter Customer Phone: " UPON CONSOLE.
    ACCEPT customer-phone FROM CONSOLE.
 
DISPLAY-CUSTOMER-DATA.
    DISPLAY "Customer Data Entered:" UPON CONSOLE.
    DISPLAY "ID: " customer-id UPON CONSOLE.
    DISPLAY "Name: " customer-name UPON CONSOLE.
    DISPLAY "Email: " customer-email UPON CONSOLE.
    DISPLAY "Phone: " customer-phone UPON CONSOLE.
    DISPLAY "=======================" UPON CONSOLE.
 
ASK-CONTINUE.
    DISPLAY "Do you want to enter another customer? (Y/N): " UPON CONSOLE.
    ACCEPT continue-entry FROM CONSOLE.
    
    * Validate input
    IF continue-entry NOT = "Y" AND continue-entry NOT = "N"
        DISPLAY "Invalid input. Please enter Y or N." UPON CONSOLE.
        PERFORM ask-continue
    END-IF.
 
DISPLAY-SUMMARY.
    DISPLAY "=== Data Entry Summary ===" UPON CONSOLE.
    DISPLAY "Total customers entered: " record-count UPON CONSOLE.
    DISPLAY "Data entry completed!" UPON CONSOLE.
    DISPLAY "=========================" UPON CONSOLE.

Data entry application using console for user input and feedback.

Best Practices

  • Provide clear and informative messages to users.
  • Validate user input to prevent errors.
  • Use consistent formatting for console output.
  • Provide helpful error messages when input is invalid.
  • Use menus and prompts to guide user interaction.
  • Consider the user experience when designing console interfaces.

Common Pitfalls

  • Not validating user input, leading to program errors.
  • Providing unclear or confusing messages to users.
  • Not handling unexpected user input gracefully.
  • Creating overly complex console interfaces.
  • Not providing adequate feedback to users.

Test Your Knowledge

1. What is CONSOLE in COBOL?

  • A data type
  • A terminal or display device for user interaction
  • A file operation
  • A program structure

2. What is the primary purpose of CONSOLE in COBOL?

  • File processing
  • User interaction and display output
  • Data storage
  • Arithmetic calculations

3. How is CONSOLE typically used in COBOL?

  • With DISPLAY statements
  • With file operations
  • With arithmetic operations
  • With data declarations

4. What type of applications use CONSOLE?

  • Only batch applications
  • Interactive applications and user interfaces
  • Only file processing applications
  • Only database applications

5. What is a common use of CONSOLE in COBOL?

  • Data storage
  • User prompts and messages
  • File operations
  • Arithmetic calculations

Frequently Asked Questions

Related Concepts

DISPLAY Statement

Using DISPLAY for output operations.

ACCEPT Statement

Using ACCEPT for input operations.

User Interface

Creating user-friendly interfaces.

Interactive Programming

Interactive programming techniques.

Input Validation

Validating user input in COBOL.

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