COBOL FILE STATUS

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ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT file-name
        ASSIGN TO 'filename'
        ORGANIZATION IS SEQUENTIAL
        FILE STATUS IS status-variable.
 
*> FILE STATUS IS: Required clause
*> status-variable: Two-character alphanumeric field
*> Automatically updated after each file operation

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IDENTIFICATION DIVISION.
PROGRAM-ID. FILE-STATUS-EXAMPLE.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT CUSTOMER-FILE
        ASSIGN TO 'CUSTOMER.DAT'
        ORGANIZATION IS SEQUENTIAL
        FILE STATUS IS CUSTOMER-STATUS.
    
    SELECT ACCOUNT-FILE
        ASSIGN TO 'ACCOUNT.DAT'
        ORGANIZATION IS INDEXED
        ACCESS MODE IS RANDOM
        RECORD KEY IS ACCOUNT-KEY
        FILE STATUS IS ACCOUNT-STATUS.
 
DATA DIVISION.
FILE SECTION.
FD  CUSTOMER-FILE
    RECORD CONTAINS 100 CHARACTERS.
01  CUSTOMER-RECORD        PIC X(100).
 
FD  ACCOUNT-FILE
    RECORD CONTAINS 80 CHARACTERS.
01  ACCOUNT-RECORD.
    05  ACCOUNT-KEY        PIC 9(8).
    05  ACCOUNT-DATA        PIC X(72).
 
WORKING-STORAGE SECTION.
*> File status variables
01  CUSTOMER-STATUS        PIC XX.
01  ACCOUNT-STATUS         PIC XX.
 
*> Condition names for readable status checking
01  FILE-STATUS-CODES.
    05  STATUS-CODE         PIC XX.
        88  FILE-OK         VALUE '00'.
        88  FILE-AT-END     VALUE '10'.
        88  FILE-DUPLICATE  VALUE '22'.
        88  FILE-NOT-FOUND  VALUE '23'.
        88  FILE-NOT-OPEN   VALUE '42'.
        88  FILE-ERROR      VALUE '30' THRU '99'.
 
PROCEDURE DIVISION.
MAIN-PROCESSING.
    *> Open file and check status
    OPEN INPUT CUSTOMER-FILE
    
    MOVE CUSTOMER-STATUS TO STATUS-CODE
    IF NOT FILE-OK
        DISPLAY 'ERROR OPENING FILE: ' CUSTOMER-STATUS
        STOP RUN
    END-IF
    
    *> Read records with status checking
    PERFORM UNTIL FILE-AT-END
        READ CUSTOMER-FILE
            AT END
                CONTINUE
            NOT AT END
                MOVE CUSTOMER-STATUS TO STATUS-CODE
                IF FILE-OK
                    *> Process record
                    DISPLAY 'RECORD READ: ' CUSTOMER-RECORD(1:20)
                ELSE
                    DISPLAY 'READ ERROR: ' CUSTOMER-STATUS
                    EXIT PERFORM
                END-IF
        END-READ
    END-PERFORM
    
    *> Close file
    CLOSE CUSTOMER-FILE
    MOVE CUSTOMER-STATUS TO STATUS-CODE
    IF NOT FILE-OK
        DISPLAY 'ERROR CLOSING FILE: ' CUSTOMER-STATUS
    END-IF
    
    STOP RUN.

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WORKING-STORAGE SECTION.
*> Define status variable
01  FILE-STATUS-CODE      PIC XX.
 
*> Use 88-level condition names for readability
01  STATUS-VALUES.
    05  STATUS-CODE        PIC XX.
        88  SUCCESS         VALUE '00'.
        88  AT-END          VALUE '10'.
        88  DUPLICATE-KEY   VALUE '22'.
        88  NOT-FOUND       VALUE '23'.
        88  FILE-NOT-FOUND  VALUE '35'.
        88  FILE-NOT-OPEN   VALUE '42'.
        88  ANY-ERROR       VALUE '01' THRU '99'
                           EXCEPT '00' '10'.
 
PROCEDURE DIVISION.
*> Always check status after file operations
    OPEN INPUT CUSTOMER-FILE
    
    MOVE CUSTOMER-STATUS TO STATUS-CODE
    EVALUATE TRUE
        WHEN SUCCESS
            DISPLAY 'FILE OPENED SUCCESSFULLY'
        WHEN FILE-NOT-FOUND
            DISPLAY 'ERROR: FILE NOT FOUND'
            STOP RUN
        WHEN ANY-ERROR
            DISPLAY 'ERROR: ' STATUS-CODE
            STOP RUN
    END-EVALUATE
    
    *> Check status after every READ
    READ CUSTOMER-FILE
    MOVE CUSTOMER-STATUS TO STATUS-CODE
    IF AT-END
        DISPLAY 'END OF FILE REACHED'
    ELSE IF NOT SUCCESS
        DISPLAY 'READ ERROR: ' STATUS-CODE
        STOP RUN
    END-IF