first_cobol_files.cbl

            IDENTIFICATION DIVISION.
            PROGRAM-ID. FILES.
            *> create an environment section
            ENVIRONMENT DIVISION.
              *> input output is where used files
              *> will be declared
              INPUT-OUTPUT SECTION.
                FILE-CONTROL.
                *> we will have one file called
                *> transactions that is sequantially written
                *> and accessed sequentially as well
                  SELECT TRANSACTIONS ASSIGN TO 'transactions.txt'
                  ORGANIZATION IS SEQUENTIAL.

            DATA DIVISION.
              FILE SECTION.
                *> create a file specification
                FD TRANSACTIONS.
                01 TRANSACTION-STRUCT.
                  02 UID PIC 9(5).
                  02 DESC PIC X(25).
                  02 DETAILS.
                    03 AMOUNT PIC 9(6)V9(2).
                    03 START-BALANCE PIC 9(6)V9(2).
                    03 END-BALANCE PIC 9(6)V9(2).
                  02 ACCOUNT-ID PIC 9(7).
                  02 ACCOUNT-HOLDER PIC A(50).

              *> create a single record for insertion
              *> this has the same structure as the
              *> record above but with actual values
              WORKING-STORAGE SECTION.
                01 TRANSACTION-RECORD.
                  02 UID PIC 9(5) VALUE 12345.
                  02 DESC PIC X(25) VALUE 'TEST TRANSACTION'.
                  02 DETAILS.
                    03 AMOUNT PIC 9(6)V9(2) VALUE 000124.34.
                    03 START-BALANCE PIC 9(6)V9(2) VALUE 000177.54.
                    03 END-BALANCE PIC 9(6)V9(2) VALUE 53.2.
                  02 ACCOUNT-ID PIC 9(7).
                  02 ACCOUNT-HOLDER PIC A(50).

            PROCEDURE DIVISION.
              *> print the record we are writing
              DISPLAY 'WRITING RECORD: 'TRANSACTION-RECORD.
              *> open the file in output mode
              *> this will re-create the file
              OPEN OUTPUT TRANSACTIONS
                *> write a record of type transaction-struct
                *> the actual record being transaction-record
                WRITE TRANSACTION-STRUCT FROM TRANSACTION-RECORD
              *> close the file
              CLOSE TRANSACTIONS
              STOP RUN.