The input file have records as: 8712351,8712353,8712353,8712354,8712356,8712352,8712355 8712352,8712355

Using COBOL, I need to remove duplicates from the above file and write to an output file. I wrote simple logic to read records and write to an output file.

Where do I need to put the logic of removing duplicates (say, 8712353, 8712352) from the above file?

Here is the program logic:

   IDENTIFICATION DIVISION.
   PROGRAM-ID.RemoveDup.
   ENVIRONMENT DIVISION.
   INPUT-OUTPUT SECTION.
   FILE-CONTROL.
   SELECT INPUTFILEDUP ASSIGN TO 'C:\Cobol\INPUTFILEDUP.txt'
           ORGANIZATION IS LINE SEQUENTIAL.
   SELECT OUTFILEDUP ASSIGN TO 'C:\Cobol\OUTFILEDUP.txt'
               ORGANIZATION IS LINE SEQUENTIAL.

   DATA DIVISION.

   FILE SECTION.
   FD INPUTFILEDUP.
   01 INPUTFILEDUPREC.
       88 EOFINPUTFILEDUP    VALUE HIGH-VALUES.
       02 INPUTFILEID        PIC 9(07).

   FD  OUTFILEDUP.
   01 OUTFILEDUPREC         PIC 9(07).

   WORKING-STORAGE SECTION.
   77 WS-VARIABLE            PIC 9(09).
   77 REC-NOT-MATCH          PIC 9(01).
   77 CUR-VARIABLE           PIC 9(09).

   PROCEDURE DIVISION.
   BEGIN.
   OPEN INPUT  INPUTFILEDUP
   OPEN OUTPUT OUTFILEDUP

   READ INPUTFILEDUP
       AT END SET EOFINPUTFILEDUP  TO TRUE
   END-READ
   PERFORM UNTIL (EOFINPUTFILEDUP)
                WRITE OUTFILEDUPREC  FROM  INPUTFILEID
               READ  INPUTFILEDUP
                     AT END SET EOFINPUTFILEDUP TO TRUE
                           PERFORM UNTIL (EOFINPUTFILEDUP)
  END-READ
  END-PERFORM
                   CLOSE   INPUTFILEDUP
                   CLOSE  OUTFILEDUP
  STOP RUN.

I sorted the tnput file in ascending order as:

8712351,8712353,8712353,8712354,8712356,8712352,8712355,8712352,8712355

And it worked, and below is the modified code:

But suppose if my file is not in either ascending or des

file cobol cobol85
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