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COBOL Tutorial

COBOL DECLARATIVES Section

The DECLARATIVES section in COBOL contains special procedures that are automatically executed when specific conditions occur, providing centralized exception handling and special processing capabilities.

DECLARATIVES Section Structure

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PROCEDURE DIVISION.
DECLARATIVES.
 
section-name SECTION.
    USE statement.
    
    paragraph-name.
        statements...
 
section-name-2 SECTION.
    USE statement.
    
    paragraph-name-2.
        statements...
 
END DECLARATIVES.
 
*> Regular procedure division code follows
MAIN-SECTION SECTION.
MAIN-PROCESSING.
    statements...

File Error Handling

USE AFTER STANDARD ERROR PROCEDURE

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PROCEDURE DIVISION.
DECLARATIVES.
 
file-error-section SECTION.
    USE AFTER STANDARD ERROR PROCEDURE ON INPUT-FILE.
    
    file-error-handler.
        DISPLAY "Error occurred on INPUT-FILE"
        DISPLAY "File Status: " FILE-STATUS-INPUT
        
        EVALUATE FILE-STATUS-INPUT
            WHEN "10"
                DISPLAY "End of file reached"
                MOVE "Y" TO EOF-FLAG
            WHEN "23"
                DISPLAY "Record not found"
                MOVE "Y" TO RECORD-NOT-FOUND-FLAG
            WHEN "24"
                DISPLAY "Boundary violation"
                PERFORM ERROR-RECOVERY
            WHEN OTHER
                DISPLAY "Unexpected file error: " FILE-STATUS-INPUT
                PERFORM ABEND-PROCESSING
        END-EVALUATE.
 
general-error-section SECTION.
    USE AFTER STANDARD ERROR PROCEDURE ON OUTPUT-FILE, REPORT-FILE.
    
    general-error-handler.
        DISPLAY "Error on file: " 
        IF FILE-STATUS-OUTPUT NOT = "00"
            DISPLAY "OUTPUT-FILE Status: " FILE-STATUS-OUTPUT
        END-IF
        IF FILE-STATUS-REPORT NOT = "00"
            DISPLAY "REPORT-FILE Status: " FILE-STATUS-REPORT
        END-IF
        PERFORM LOG-ERROR-DETAILS.
 
END DECLARATIVES.
 
MAIN-SECTION SECTION.
MAIN-PROCESSING.
    OPEN INPUT INPUT-FILE
    OPEN OUTPUT OUTPUT-FILE, REPORT-FILE
    
    PERFORM READ-AND-PROCESS UNTIL EOF-FLAG = "Y"
    
    CLOSE INPUT-FILE, OUTPUT-FILE, REPORT-FILE
    STOP RUN.
 
READ-AND-PROCESS.
    READ INPUT-FILE
        AT END MOVE "Y" TO EOF-FLAG
        NOT AT END PERFORM PROCESS-RECORD
    END-READ.
 
ERROR-RECOVERY.
    DISPLAY "Attempting error recovery..."
    *> Recovery logic here
 
ABEND-PROCESSING.
    DISPLAY "Fatal error - terminating program"
    MOVE 16 TO RETURN-CODE
    STOP RUN.
 
LOG-ERROR-DETAILS.
    *> Log error to audit file or system log
    CONTINUE.

Advanced File Error Processing

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DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-ERROR-HANDLING.
   05 WS-ERROR-COUNT        PIC 9(3) VALUE ZERO.
   05 WS-MAX-ERRORS         PIC 9(3) VALUE 10.
   05 WS-RETRY-COUNT        PIC 9(2) VALUE ZERO.
   05 WS-MAX-RETRIES        PIC 9(2) VALUE 3.
   05 WS-ERROR-LOG-FILE     PIC X(20) VALUE "ERROR.LOG".
 
01 WS-ERROR-DETAILS.
   05 WS-ERROR-TIMESTAMP    PIC X(20).
   05 WS-ERROR-FILE-NAME    PIC X(30).
   05 WS-ERROR-STATUS       PIC X(2).
   05 WS-ERROR-OPERATION    PIC X(10).
 
PROCEDURE DIVISION.
DECLARATIVES.
 
comprehensive-error-section SECTION.
    USE AFTER STANDARD ERROR PROCEDURE ON ALL FILES.
    
    comprehensive-error-handler.
        ADD 1 TO WS-ERROR-COUNT
        ACCEPT WS-ERROR-TIMESTAMP FROM DATE-TIME
        
        *> Determine which file caused the error
        PERFORM IDENTIFY-ERROR-FILE
        
        *> Log the error
        PERFORM LOG-COMPREHENSIVE-ERROR
        
        *> Determine recovery action
        PERFORM DETERMINE-ERROR-ACTION.
 
END DECLARATIVES.
 
MAIN-SECTION SECTION.
IDENTIFY-ERROR-FILE.
    *> Check file status of all files to identify the problem
    IF FILE-STATUS-CUSTOMER NOT = "00"
        MOVE "CUSTOMER-FILE" TO WS-ERROR-FILE-NAME
        MOVE FILE-STATUS-CUSTOMER TO WS-ERROR-STATUS
    ELSE IF FILE-STATUS-ORDERS NOT = "00"
        MOVE "ORDERS-FILE" TO WS-ERROR-FILE-NAME
        MOVE FILE-STATUS-ORDERS TO WS-ERROR-STATUS
    ELSE IF FILE-STATUS-REPORTS NOT = "00"
        MOVE "REPORTS-FILE" TO WS-ERROR-FILE-NAME
        MOVE FILE-STATUS-REPORTS TO WS-ERROR-STATUS
    END-IF.
 
LOG-COMPREHENSIVE-ERROR.
    DISPLAY "=== FILE ERROR DETECTED ==="
    DISPLAY "Timestamp: " WS-ERROR-TIMESTAMP
    DISPLAY "File: " WS-ERROR-FILE-NAME
    DISPLAY "Status: " WS-ERROR-STATUS
    DISPLAY "Error Count: " WS-ERROR-COUNT
    DISPLAY "=========================="
    
    *> Write to error log file
    PERFORM WRITE-ERROR-LOG.
 
DETERMINE-ERROR-ACTION.
    EVALUATE WS-ERROR-STATUS
        WHEN "10"  *> End of file
            CONTINUE
        WHEN "23"  *> Record not found
            IF WS-RETRY-COUNT < WS-MAX-RETRIES
                ADD 1 TO WS-RETRY-COUNT
                DISPLAY "Retrying operation..."
            ELSE
                DISPLAY "Max retries exceeded"
                PERFORM SKIP-RECORD-PROCESSING
            END-IF
        WHEN "30"  *> Permanent error
            DISPLAY "Permanent error - cannot continue"
            PERFORM EMERGENCY-SHUTDOWN
        WHEN OTHER
            IF WS-ERROR-COUNT > WS-MAX-ERRORS
                DISPLAY "Too many errors - aborting"
                PERFORM EMERGENCY-SHUTDOWN
            ELSE
                DISPLAY "Continuing with next operation"
            END-IF
    END-EVALUATE.
 
WRITE-ERROR-LOG.
    *> Write detailed error information to log file
    CONTINUE.
 
SKIP-RECORD-PROCESSING.
    *> Skip current record and continue
    CONTINUE.
 
EMERGENCY-SHUTDOWN.
    DISPLAY "Emergency shutdown initiated"
    MOVE 20 TO RETURN-CODE
    STOP RUN.

Report Writer Declaratives

USE BEFORE REPORTING

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PROCEDURE DIVISION.
DECLARATIVES.
 
report-control-section SECTION.
    USE BEFORE REPORTING PAGE-HEADING.
    
    page-heading-control.
        ADD 1 TO PAGE-COUNTER
        ACCEPT CURRENT-DATE-TIME FROM DATE-TIME
        MOVE CURRENT-DATE-TIME(1:8) TO REPORT-DATE
        MOVE CURRENT-DATE-TIME(9:6) TO REPORT-TIME
        
        DISPLAY "Generating page " PAGE-COUNTER.
 
summary-control-section SECTION.
    USE BEFORE REPORTING FINAL-SUMMARY.
    
    final-summary-control.
        COMPUTE AVERAGE-AMOUNT = TOTAL-AMOUNT / RECORD-COUNT
        MOVE AVERAGE-AMOUNT TO AVERAGE-DISPLAY
        
        DISPLAY "Final summary being generated"
        DISPLAY "Total records processed: " RECORD-COUNT
        DISPLAY "Average amount: " AVERAGE-DISPLAY.
 
END DECLARATIVES.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-COUNTERS.
   05 PAGE-COUNTER          PIC 9(3) VALUE ZERO.
   05 RECORD-COUNT          PIC 9(5) VALUE ZERO.
   05 TOTAL-AMOUNT          PIC 9(8)V99 VALUE ZERO.
   05 AVERAGE-AMOUNT        PIC 9(6)V99.
 
01 WS-DATE-TIME-FIELDS.
   05 CURRENT-DATE-TIME     PIC X(20).
   05 REPORT-DATE           PIC X(8).
   05 REPORT-TIME           PIC X(6).
 
01 WS-DISPLAY-FIELDS.
   05 AVERAGE-DISPLAY       PIC ZZ,ZZ9.99.
 
REPORT SECTION.
RD SALES-REPORT
    CONTROL IS FINAL, REGION.
 
01 PAGE-HEADING TYPE IS PAGE HEADING.
   05 LINE 1.
   05 COLUMN 1     PIC X(20) VALUE "SALES REPORT".
   05 COLUMN 50    PIC X(8) SOURCE REPORT-DATE.
   05 COLUMN 60    PIC X(6) SOURCE REPORT-TIME.
   05 COLUMN 70    PIC X(5) VALUE "PAGE ".
   05 COLUMN 75    PIC ZZ9 SOURCE PAGE-COUNTER.
 
01 DETAIL-LINE TYPE IS DETAIL.
   05 LINE PLUS 1.
   05 COLUMN 1     PIC X(10) SOURCE SALESMAN-ID.
   05 COLUMN 15    PIC X(20) SOURCE CUSTOMER-NAME.
   05 COLUMN 40    PIC ZZ,ZZ9.99 SOURCE SALE-AMOUNT.
 
01 FINAL-SUMMARY TYPE IS CONTROL FOOTING FINAL.
   05 LINE PLUS 3.
   05 COLUMN 1     PIC X(15) VALUE "TOTAL RECORDS: ".
   05 COLUMN 20    PIC ZZ,ZZ9 SOURCE RECORD-COUNT.
   05 LINE PLUS 1.
   05 COLUMN 1     PIC X(15) VALUE "AVERAGE AMOUNT: ".
   05 COLUMN 20    PIC ZZ,ZZ9.99 SOURCE AVERAGE-DISPLAY.

Complex Report Processing

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PROCEDURE DIVISION.
DECLARATIVES.
 
region-break-section SECTION.
    USE BEFORE REPORTING REGION-FOOTING.
    
    region-break-processing.
        *> Calculate region statistics
        IF REGION-RECORD-COUNT > 0
            COMPUTE REGION-AVERAGE = 
                REGION-TOTAL / REGION-RECORD-COUNT
        ELSE
            MOVE ZERO TO REGION-AVERAGE
        END-IF
        
        *> Determine performance rating
        EVALUATE TRUE
            WHEN REGION-TOTAL > 100000
                MOVE "EXCELLENT" TO REGION-RATING
            WHEN REGION-TOTAL > 50000
                MOVE "GOOD" TO REGION-RATING
            WHEN REGION-TOTAL > 25000
                MOVE "AVERAGE" TO REGION-RATING
            WHEN OTHER
                MOVE "BELOW AVG" TO REGION-RATING
        END-EVALUATE
        
        *> Log region completion
        DISPLAY "Region " REGION-CODE " completed:"
        DISPLAY "  Records: " REGION-RECORD-COUNT
        DISPLAY "  Total: " REGION-TOTAL
        DISPLAY "  Average: " REGION-AVERAGE
        DISPLAY "  Rating: " REGION-RATING.
 
page-overflow-section SECTION.
    USE BEFORE REPORTING PAGE-FOOTING.
    
    page-overflow-processing.
        *> Check if page is getting full
        IF LINE-COUNTER > 50
            DISPLAY "Page " PAGE-COUNTER " is full - starting new page"
            ADD 1 TO TOTAL-PAGES
        END-IF
        
        *> Add page footer information
        ACCEPT CURRENT-TIME FROM TIME
        MOVE CURRENT-TIME TO PAGE-TIME.
 
END DECLARATIVES.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-REGION-STATS.
   05 REGION-RECORD-COUNT   PIC 9(4) VALUE ZERO.
   05 REGION-TOTAL          PIC 9(8)V99 VALUE ZERO.
   05 REGION-AVERAGE        PIC 9(6)V99.
   05 REGION-RATING         PIC X(10).
 
01 WS-PAGE-CONTROL.
   05 TOTAL-PAGES           PIC 9(3) VALUE ZERO.
   05 LINE-COUNTER          PIC 9(2) VALUE ZERO.
   05 CURRENT-TIME          PIC X(8).
   05 PAGE-TIME             PIC X(8).
 
REPORT SECTION.
RD REGIONAL-SALES-REPORT
    CONTROL IS FINAL, REGION-CODE.
 
01 REGION-FOOTING TYPE IS CONTROL FOOTING REGION-CODE.
   05 LINE PLUS 2.
   05 COLUMN 1     PIC X(15) VALUE "REGION TOTAL: ".
   05 COLUMN 20    PIC ZZ,ZZ9.99 SOURCE REGION-TOTAL.
   05 COLUMN 35    PIC X(10) VALUE "AVERAGE: ".
   05 COLUMN 45    PIC Z,ZZ9.99 SOURCE REGION-AVERAGE.
   05 COLUMN 55    PIC X(10) VALUE "RATING: ".
   05 COLUMN 65    PIC X(10) SOURCE REGION-RATING.
 
01 PAGE-FOOTING TYPE IS PAGE FOOTING.
   05 LINE 60.
   05 COLUMN 1     PIC X(20) VALUE "End of Page".
   05 COLUMN 50    PIC X(8) SOURCE PAGE-TIME.

Exception Handling Declaratives

USE AFTER STANDARD EXCEPTION PROCEDURE

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PROCEDURE DIVISION.
DECLARATIVES.
 
exception-handling-section SECTION.
    USE AFTER STANDARD EXCEPTION PROCEDURE.
    
    exception-handler.
        DISPLAY "Exception occurred in program"
        DISPLAY "Exception type: " EXCEPTION-TYPE
        DISPLAY "Exception location: " EXCEPTION-LOCATION
        
        PERFORM LOG-EXCEPTION-DETAILS
        PERFORM DETERMINE-EXCEPTION-ACTION.
 
arithmetic-exception-section SECTION.
    USE AFTER STANDARD EXCEPTION PROCEDURE ON ARITHMETIC-OPERATIONS.
    
    arithmetic-exception-handler.
        DISPLAY "Arithmetic exception detected"
        EVALUATE EXCEPTION-TYPE
            WHEN "DIVIDE-BY-ZERO"
                DISPLAY "Division by zero attempted"
                PERFORM HANDLE-DIVIDE-BY-ZERO
            WHEN "OVERFLOW"
                DISPLAY "Arithmetic overflow occurred"
                PERFORM HANDLE-OVERFLOW
            WHEN "SIZE-ERROR"
                DISPLAY "Size error in arithmetic operation"
                PERFORM HANDLE-SIZE-ERROR
            WHEN OTHER
                DISPLAY "Unknown arithmetic exception"
                PERFORM HANDLE-UNKNOWN-ARITHMETIC-ERROR
        END-EVALUATE.
 
END DECLARATIVES.
 
MAIN-SECTION SECTION.
LOG-EXCEPTION-DETAILS.
    ACCEPT EXCEPTION-TIMESTAMP FROM DATE-TIME
    
    DISPLAY "=== EXCEPTION LOG ==="
    DISPLAY "Time: " EXCEPTION-TIMESTAMP
    DISPLAY "Type: " EXCEPTION-TYPE
    DISPLAY "Location: " EXCEPTION-LOCATION
    DISPLAY "Program: " PROGRAM-NAME
    DISPLAY "===================="
    
    *> Write to exception log file
    PERFORM WRITE-EXCEPTION-LOG.
 
DETERMINE-EXCEPTION-ACTION.
    EVALUATE EXCEPTION-SEVERITY
        WHEN "FATAL"
            DISPLAY "Fatal exception - terminating"
            PERFORM CLEANUP-AND-EXIT
        WHEN "ERROR"
            DISPLAY "Error exception - attempting recovery"
            PERFORM ATTEMPT-RECOVERY
        WHEN "WARNING"
            DISPLAY "Warning exception - continuing"
            CONTINUE
        WHEN OTHER
            DISPLAY "Unknown exception severity"
            PERFORM ATTEMPT-RECOVERY
    END-EVALUATE.
 
HANDLE-DIVIDE-BY-ZERO.
    DISPLAY "Setting result to zero for divide-by-zero"
    MOVE ZERO TO CALCULATION-RESULT
    ADD 1 TO DIVIDE-BY-ZERO-COUNT.
 
HANDLE-OVERFLOW.
    DISPLAY "Using maximum value for overflow"
    MOVE HIGH-VALUES TO CALCULATION-RESULT
    ADD 1 TO OVERFLOW-COUNT.
 
HANDLE-SIZE-ERROR.
    DISPLAY "Truncating result for size error"
    MOVE 999999999 TO CALCULATION-RESULT
    ADD 1 TO SIZE-ERROR-COUNT.
 
HANDLE-UNKNOWN-ARITHMETIC-ERROR.
    DISPLAY "Setting default value for unknown error"
    MOVE ZERO TO CALCULATION-RESULT
    ADD 1 TO UNKNOWN-ERROR-COUNT.
 
WRITE-EXCEPTION-LOG.
    *> Write exception details to log file
    CONTINUE.
 
ATTEMPT-RECOVERY.
    DISPLAY "Attempting automatic recovery..."
    *> Recovery logic here
    CONTINUE.
 
CLEANUP-AND-EXIT.
    DISPLAY "Performing cleanup operations..."
    *> Cleanup logic here
    MOVE 24 TO RETURN-CODE
    STOP RUN.

Best Practices and Guidelines

DECLARATIVES Best Practices

  • Keep declarative procedures simple and focused on their specific purpose
  • Always include proper error logging and recovery mechanisms
  • Use meaningful section and paragraph names for clarity
  • Avoid complex logic in declarative procedures
  • Test all declarative procedures thoroughly with various error conditions
  • Document the purpose and trigger conditions for each declarative
  • Consider performance impact of declarative processing

Common Patterns and Templates

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*> Standard DECLARATIVES template
PROCEDURE DIVISION.
DECLARATIVES.
 
*> File error handling template
file-error-section SECTION.
    USE AFTER STANDARD ERROR PROCEDURE ON file-name.
    
    file-error-handler.
        PERFORM LOG-FILE-ERROR
        PERFORM DETERMINE-FILE-ACTION.
 
*> Report processing template  
report-section SECTION.
    USE BEFORE REPORTING report-group-name.
    
    report-handler.
        PERFORM SETUP-REPORT-DATA
        PERFORM CALCULATE-REPORT-TOTALS.
 
*> Debug processing template
debug-section SECTION.
    USE FOR DEBUGGING ON ALL PROCEDURES.
    
    debug-handler.
        IF DEBUG-MODE-ON
            PERFORM LOG-DEBUG-INFO
        END-IF.
 
*> Exception handling template
exception-section SECTION.
    USE AFTER STANDARD EXCEPTION PROCEDURE.
    
    exception-handler.
        PERFORM LOG-EXCEPTION
        PERFORM HANDLE-EXCEPTION.
 
END DECLARATIVES.
 
*> Standard procedures for declaratives
MAIN-SECTION SECTION.
LOG-FILE-ERROR.
    DISPLAY "File error: " FILE-STATUS
    *> Log to error file or system log
 
DETERMINE-FILE-ACTION.
    EVALUATE FILE-STATUS
        WHEN "10" CONTINUE  *> End of file
        WHEN "23" PERFORM RETRY-OPERATION
        WHEN OTHER PERFORM ABORT-PROCESSING
    END-EVALUATE.
 
LOG-DEBUG-INFO.
    DISPLAY "Debug: " DEBUG-LINE " " DEBUG-NAME.
 
LOG-EXCEPTION.
    DISPLAY "Exception: " EXCEPTION-TYPE.
 
HANDLE-EXCEPTION.
    EVALUATE EXCEPTION-TYPE
        WHEN "FATAL" PERFORM EMERGENCY-EXIT
        WHEN OTHER PERFORM CONTINUE-PROCESSING
    END-EVALUATE.

Related Concepts

Exception Handling

Error and exception processing techniques in COBOL programs

File Processing

File operations and I/O error handling strategies

Program Structure

Understanding COBOL program organization and sections

Debugging Techniques

Advanced debugging and troubleshooting methods

Frequently Asked Questions