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COBOL USE AFTER STANDARD EXCEPTION PROCEDURE - Quick Reference

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Overview

USE AFTER STANDARD EXCEPTION PROCEDURE is a COBOL feature that allows you to define a centralized exception handling procedure for standard system exceptions. It provides a structured way to handle exceptions that occur during program execution, enabling consistent error recovery and improved program reliability.

Purpose and Usage

  • Centralized exception handling for standard exceptions
  • Consistent error recovery mechanisms
  • Improved program reliability
  • Standardized error responses
  • System-level error management

Syntax

USE AFTER STANDARD EXCEPTION PROCEDURE is declared in the ENVIRONMENT DIVISION:

Basic Declaration

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* Basic USE AFTER STANDARD EXCEPTION PROCEDURE
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
SPECIAL-NAMES.
    USE AFTER STANDARD EXCEPTION PROCEDURE exception-handler.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
01  error-message PIC X(100).
 
PROCEDURE DIVISION.
MAIN-PROCESS.
    * Program logic here
    PERFORM normal-processing.
    STOP RUN.
 
* Exception handling procedure
EXCEPTION-HANDLER.
    * Handle standard exceptions
    DISPLAY "Standard exception occurred".
    PERFORM error-recovery.
    EXIT PROGRAM.

The exception procedure is automatically called when standard exceptions occur.

Exception Handling Implementation

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* Comprehensive exception handling
EXCEPTION-HANDLER.
    * Log the exception
    DISPLAY "Exception occurred at: " FUNCTION CURRENT-DATE.
    
    * Determine exception type and handle accordingly
    IF arithmetic-exception
        DISPLAY "Arithmetic exception detected"
        PERFORM arithmetic-error-recovery
    ELSE IF file-exception
        DISPLAY "File exception detected"
        PERFORM file-error-recovery
    ELSE IF system-exception
        DISPLAY "System exception detected"
        PERFORM system-error-recovery
    ELSE
        DISPLAY "Unknown exception detected"
        PERFORM general-error-recovery
    END-IF.
    
    * Perform cleanup
    PERFORM cleanup-procedures.
    
    * Exit program or continue as appropriate
    EXIT PROGRAM.
 
ARITHMETIC-ERROR-RECOVERY.
    DISPLAY "Handling arithmetic error".
    * Specific arithmetic error handling logic.
 
FILE-ERROR-RECOVERY.
    DISPLAY "Handling file error".
    * Specific file error handling logic.
 
SYSTEM-ERROR-RECOVERY.
    DISPLAY "Handling system error".
    * Specific system error handling logic.

Practical Examples

Here are some practical uses of USE AFTER STANDARD EXCEPTION PROCEDURE in COBOL:

File Processing with Exception Handling

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* File processing with standard exception handling
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
SPECIAL-NAMES.
    USE AFTER STANDARD EXCEPTION PROCEDURE file-exception-handler.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
01  file-status PIC XX.
01  error-log PIC X(200).
 
PROCEDURE DIVISION.
PROCESS-FILES.
    * Open and process files
    OPEN INPUT data-file.
    PERFORM UNTIL end-of-file
        READ data-file
            AT END
                MOVE "Y" TO end-of-file-flag
            NOT AT END
                PERFORM process-record
        END-READ
    END-PERFORM.
    CLOSE data-file.
    STOP RUN.
 
* Standard exception handler for file operations
FILE-EXCEPTION-HANDLER.
    * Log the exception details
    MOVE FUNCTION CURRENT-DATE TO error-log.
    DISPLAY "File exception: " error-log.
    
    * Handle specific file exceptions
    IF file-not-found
        DISPLAY "File not found - using default file"
        PERFORM use-default-file
    ELSE IF access-denied
        DISPLAY "Access denied - checking permissions"
        PERFORM check-file-permissions
    ELSE IF file-corrupted
        DISPLAY "File corrupted - attempting recovery"
        PERFORM file-recovery
    ELSE
        DISPLAY "Unknown file error - terminating"
        PERFORM graceful-shutdown
    END-IF.
    
    EXIT PROGRAM.
 
USE-DEFAULT-FILE.
    * Logic to use default file
    DISPLAY "Switching to default file".
 
CHECK-FILE-PERMISSIONS.
    * Logic to check and fix permissions
    DISPLAY "Checking file permissions".
 
FILE-RECOVERY.
    * Logic to recover corrupted file
    DISPLAY "Attempting file recovery".
 
GRACEFUL-SHUTDOWN.
    * Logic for graceful program termination
    DISPLAY "Performing graceful shutdown".

Comprehensive file processing with standard exception handling.

Arithmetic Operations with Exception Handling

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* Arithmetic operations with exception handling
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
SPECIAL-NAMES.
    USE AFTER STANDARD EXCEPTION PROCEDURE arithmetic-exception-handler.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
01  result PIC 9(10)V99.
01  divisor PIC 9(5).
01  dividend PIC 9(5).
 
PROCEDURE DIVISION.
CALCULATE-RESULTS.
    * Perform arithmetic operations
    MOVE 100 TO dividend.
    MOVE 5 TO divisor.
    
    DIVIDE dividend BY divisor GIVING result.
    DISPLAY "Result: " result.
    
    * Try division by zero (will trigger exception)
    MOVE 0 TO divisor.
    DIVIDE dividend BY divisor GIVING result.
    
    STOP RUN.
 
* Standard exception handler for arithmetic operations
ARITHMETIC-EXCEPTION-HANDLER.
    * Log arithmetic exception
    DISPLAY "Arithmetic exception detected".
    
    * Handle specific arithmetic exceptions
    IF division-by-zero
        DISPLAY "Division by zero detected"
        PERFORM handle-division-by-zero
    ELSE IF overflow
        DISPLAY "Arithmetic overflow detected"
        PERFORM handle-overflow
    ELSE IF underflow
        DISPLAY "Arithmetic underflow detected"
        PERFORM handle-underflow
    ELSE
        DISPLAY "Unknown arithmetic error"
        PERFORM handle-unknown-arithmetic-error
    END-IF.
    
    EXIT PROGRAM.
 
HANDLE-DIVISION-BY-ZERO.
    DISPLAY "Setting result to zero for division by zero".
    MOVE ZERO TO result.
 
HANDLE-OVERFLOW.
    DISPLAY "Handling arithmetic overflow".
    MOVE 9999999999 TO result.
 
HANDLE-UNDERFLOW.
    DISPLAY "Handling arithmetic underflow".
    MOVE ZERO TO result.
 
HANDLE-UNKNOWN-ARITHMETIC-ERROR.
    DISPLAY "Handling unknown arithmetic error".
    MOVE ZERO TO result.

Arithmetic operations with comprehensive exception handling.

Best Practices

  • Use this feature for centralized exception handling in production applications.
  • Implement specific handling for different types of exceptions.
  • Provide meaningful error messages and logging.
  • Perform appropriate cleanup in exception handlers.
  • Consider the impact on program flow and termination.
  • Test exception handling thoroughly.

Common Pitfalls

  • Not handling all possible exception types.
  • Providing generic error messages that don\'t help with debugging.
  • Not performing proper cleanup in exception handlers.
  • Infinite loops in exception handling procedures.
  • Not considering the impact on program termination.

Test Your Knowledge

1. What is USE AFTER STANDARD EXCEPTION PROCEDURE in COBOL?

  • A file operation
  • An exception handling mechanism
  • A data declaration
  • A program structure

2. Where is USE AFTER STANDARD EXCEPTION PROCEDURE declared?

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

3. What types of exceptions does it handle?

  • Only file exceptions
  • Only arithmetic exceptions
  • Standard system exceptions
  • Only user-defined exceptions

4. When is the exception procedure executed?

  • Before program execution
  • After a standard exception occurs
  • During compilation
  • At program termination

5. What is the primary purpose of this feature?

  • To improve performance
  • To provide centralized exception handling
  • To reduce memory usage
  • To simplify program logic

Frequently Asked Questions

Related Concepts

Exception Handling

Comprehensive exception handling in COBOL.

ON EXCEPTION

Handling exceptions in COBOL.

Error Handling

Error handling strategies and best practices.

File Processing

File operations with error handling.

Robust Programming

Best practices for reliable COBOL programs.

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