Linux Notes: indexed-file-demo2.cob

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Edit: 2026-09-23
Back to: Linux Notes: GnuCOBOL

indexed-file-demo2.cob

• The code:

        * ===============================================================
        * FILE : indexed-file-demo2.cob
        * NOTES:
        * 1) this program is a modified version of the demo cobol program
        *    sent by Roland.
        *
        * 2) It contains a few hacks (starting at line 100) so that it
        *    will compile as-is when using cobc (GnuCobol 3.2.0). The
        *    orginal failure is due to the fact that the original cobol
        *    spec has a default right limit of 72 (this comes from the
        *    days of punched cards). Compile this program like so:
        *
        *       cobc -x                   indexed-file-demo2.cob
        *
        * Neil Rieck (2026-09-22)
        * ===============================================================
         IDENTIFICATION DIVISION.
         PROGRAM-ID. INDEXED-DEMO.
  
         ENVIRONMENT DIVISION.
         INPUT-OUTPUT SECTION.
         FILE-CONTROL.
             SELECT OPTIONAL EMP-FILE
                 ASSIGN TO "EMPLOYEE.DAT"
                 ORGANIZATION IS INDEXED
                 ACCESS MODE IS DYNAMIC
                 RECORD KEY IS EMP-ID
                 FILE STATUS IS WS-FS.
  
         DATA DIVISION.
         FILE SECTION.
         FD  EMP-FILE.
         01  EMP-RECORD.
             05  EMP-ID        PIC 9(4).
             05  EMP-NAME      PIC X(20).
             05  EMP-DEPT      PIC X(10).
  
         WORKING-STORAGE SECTION.
         01  BUFFER132         PIC X(132).
         01  WS-FS             PIC XX.
         01  WS-EOF-SWITCH     PIC X         VALUE "N".
             88  END-OF-FILE                 VALUE "Y".
         PROCEDURE DIVISION.
         MAIN-LOGIC.
        *    1. Open the file in I-O mode (reads, writes, and updates allowed)
             OPEN I-O EMP-FILE
             IF WS-FS = "35"
        *        File didn't exist; Open as OUTPUT to create it initially
                 OPEN OUTPUT EMP-FILE
                 CLOSE EMP-FILE
                 OPEN I-O EMP-FILE
             END-IF
  
        *    2. Write records to the indexed file
             DISPLAY "--- WRITING RECORDS ---"
             END-DISPLAY
             PERFORM WRITE-SAMPLE-DATA
  
        *    3. Random access lookup (Direct retrieval using key)
             DISPLAY " "
             DISPLAY "--- RANDOM ACCESS LOOKUP ---"
             END-DISPLAY
             PERFORM READ-RANDOM-RECORD
  
        *    4. Sequential readout (Indexed files automatically sort by key)
             DISPLAY " "
             DISPLAY "--- SEQUENTIAL READOUT (SORTED BY KEY) ---"
             PERFORM READ-ALL-SEQUENTIAL
  
             CLOSE EMP-FILE
             STOP RUN.
  
         WRITE-SAMPLE-DATA.
             MOVE 1003 TO EMP-ID
             MOVE "Alice Smith" TO EMP-NAME
             MOVE "Engineering" TO EMP-DEPT
             PERFORM WRITE-RECORD
  
             MOVE 1001 TO EMP-ID
             MOVE "Bob Jones" TO EMP-NAME
             MOVE "Marketing" TO EMP-DEPT
             PERFORM WRITE-RECORD
  
             MOVE 1002 TO EMP-ID
             MOVE "Charlie Brown" TO EMP-NAME
             MOVE "Finance" TO EMP-DEPT
             PERFORM WRITE-RECORD.
  
         WRITE-RECORD.
             WRITE EMP-RECORD
                 INVALID KEY
                     DISPLAY "ERROR: Duplicate Key " EMP-ID "!"
                 NOT INVALID KEY
                     DISPLAY "Successfully wrote: " EMP-ID " - " EMP-NAME
             END-WRITE.
  
         READ-RANDOM-RECORD.
        *    Set the primary key to find exactly what we want
             MOVE 1002 TO EMP-ID
             READ EMP-FILE
                 INVALID KEY
                     DISPLAY "Record " EMP-ID " not found."
                 NOT INVALID KEY
        *
        * Caveat: cobc (guncobol) has a default right limit 72 (this goes
        * back to the punched card days)
        *
        * 1) This original source line from another program fails (
        *    unless you compile with switch: -ftext-column=132
        *            DISPLAY "Found Key 1002 -> " EMP-NAME " (" EMP-DEPT ")"
        *    ----------------------------
        * 2) This alternate syntax works
                     DISPLAY "Found Key 1002 -> " EMP-NAME
                             " (" EMP-DEPT ")"
                     END-DISPLAY
        *    ----------------------------
        * 3) Copying to a temporary string also works
        *            STRING  "Found Key 1002 -> " EMP-NAME
        *                     " (" EMP-DEPT ")"
        *                     INTO BUFFER132
        *            END-STRING
        *            DISPLAY BUFFER132
        *    ----------------------------
             END-READ.
  
         READ-ALL-SEQUENTIAL.
        *    Point the index back to the beginning of the file
             MOVE 0000 TO EMP-ID
             START EMP-FILE KEY IS GREATER THAN EMP-ID
                 INVALID KEY
                     DISPLAY "No records to read."
             END-START
  
        *    Loop through the file sequentially
             PERFORM UNTIL END-OF-FILE
                 READ EMP-FILE NEXT RECORD
                     AT END
                         SET END-OF-FILE TO TRUE
                     NOT AT END
                         DISPLAY "Seq Record: ID=" EMP-ID
                                 " Name=" EMP-NAME
                                 " Dept=" EMP-DEPT
                 END-READ
             END-PERFORM.
  

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Neil Rieck
Waterloo, Ontario, Canada.