💻 COBOL

COBOL OPEN Statement

Intermediate 🕑 10 min read 👁 1 views

COBOL OPEN Statement

The OPEN statement makes a file available for processing.

Syntax

OPEN INPUT file-name
OPEN OUTPUT file-name
OPEN I-O file-name
OPEN EXTEND file-name

Open Modes

Mode	Purpose
INPUT	Read only
OUTPUT	Write new file
I-O	Read and update
EXTEND	Append to file

Example Program

       IDENTIFICATION DIVISION.
       PROGRAM-ID. OPEN-DEMO.

       ENVIRONMENT DIVISION.
       INPUT-OUTPUT SECTION.
       FILE-CONTROL.
           SELECT INPUT-FILE ASSIGN TO 'INPUT.DAT'
               FILE STATUS IS WS-FILE-STATUS.
           SELECT OUTPUT-FILE ASSIGN TO 'OUTPUT.DAT'
               FILE STATUS IS WS-OUT-STATUS.

       DATA DIVISION.
       FILE SECTION.
       FD INPUT-FILE.
       01 INPUT-RECORD    PIC X(80).
       FD OUTPUT-FILE.
       01 OUTPUT-RECORD   PIC X(80).

       WORKING-STORAGE SECTION.
       01 WS-FILE-STATUS  PIC XX VALUE SPACES.
       01 WS-OUT-STATUS   PIC XX VALUE SPACES.

       PROCEDURE DIVISION.
           OPEN INPUT INPUT-FILE
           IF WS-FILE-STATUS NOT = '00'
               DISPLAY 'Error opening input: ' WS-FILE-STATUS
               STOP RUN
           END-IF
           DISPLAY 'Input file opened successfully'

           OPEN OUTPUT OUTPUT-FILE
           IF WS-OUT-STATUS NOT = '00'
               DISPLAY 'Error opening output: ' WS-OUT-STATUS
               STOP RUN
           END-IF
           DISPLAY 'Output file opened successfully'

           CLOSE INPUT-FILE OUTPUT-FILE
           STOP RUN.

Expected Output

Input file opened successfully
Output file opened successfully

Key Points

Always check FILE STATUS after OPEN
OUTPUT creates new file (overwrites existing)
EXTEND appends to existing file
I-O requires file to exist