How to Read a Variable Length File in COBOL

COBOL programs can process variable-length records stored in database files.

IBM's Common Business Oriented Language (COBOL) programming language allows users to process different types of data in financial and business software applications. COBOL supports the variable-length records data type for use in database files stored on hard disks; the user specifies the maximum and minimum record lengths for describing disk files with variable-length records. Reading variable-length data from a file allows you to process database information without defining the exact size of a record in your COBOL program.

Instructions

1. Type "Edit" on the z/OS360 mainframe system-management console and press the "Enter" key to edit your COBOL program.

2. Add the following code to the beginning of your program:

   IDENTIFICATION DIVISION.

   PROGRAM-ID. COBVAR.

   ENVIRONMENT DIVISION.

   INPUT-OUTPUT SECTION.

   FILE-CONTROL.

   SELECT IFILE ASSIGN TO "IFILE".

   DATA DIVISION.

   FILE SECTION.

   FD IFILE

   RECORD IS VARYING FROM 10 TO 50 DEPENDING ON LEN.

   01 IREC.

   05 FILLER PIC X OCCURS 10 TO 50 TIMES DEPENDING ON LEN.

   PROCEDURE DIVISION.

   P1.

   DISPLAY "EXAMPLE 1 OCCURS DEPENDING ON REC"

   OPEN INPUT IFILE

   PERFORM UNTIL LEN = -1

   READ IFILE

   AT END MOVE -1 TO LEN

   NOT AT END

   DISPLAY IREC

   DISPLAY LEN

   END-READ

   END-PERFORM

   CLOSE IFILE

   DISPLAY SPACE

   DISPLAY "EXAMPLE FIXED REC"

   OPEN INPUT IFILE

   MOVE ALL "X" TO IREC

   READ IFILE AT END MOVE -1 TO LEN

   DISPLAY IREC

   DISPLAY SPACE

3. Type "Save" on the console and press the "Enter" key to enable your program to process variable-length records.

References

• HP: COBOL II/XL Programmer's Guide: Logical Files