Learn COBOL with Real Code Examples

       IDENTIFICATION DIVISION.
       PROGRAM-ID. CounterProgram.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 COUNT        PIC 9(4) VALUE 0.
       01 IS-DARK      PIC X VALUE 'N'.

       PROCEDURE DIVISION.
       DISPLAY 'Counter: ' COUNT
       DISPLAY 'Theme: ' IS-DARK

       ADD 1 TO COUNT
       DISPLAY 'Counter: ' COUNT

       MOVE 'Y' TO IS-DARK
       DISPLAY 'Theme: ' IS-DARK

       SUBTRACT 1 FROM COUNT
       DISPLAY 'Counter: ' COUNT

       MOVE 0 TO COUNT
       DISPLAY 'Counter: ' COUNT

       STOP RUN.

Demonstrates a simple counter with theme toggling using COBOL variables and console output.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. AddProgram.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 A   PIC 9(4) VALUE 5.
       01 B   PIC 9(4) VALUE 3.
       01 SUM PIC 9(4) VALUE 0.

       PROCEDURE DIVISION.
       ADD A TO B GIVING SUM
       DISPLAY 'Sum: ' SUM
       STOP RUN.

Adds two numbers and displays the result.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. FactorialProgram.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 N       PIC 9(2) VALUE 5.
       01 FACT    PIC 9(5) VALUE 1.
       01 COUNTER PIC 9(2) VALUE 1.

       PROCEDURE DIVISION.
       PERFORM VARYING COUNTER FROM 1 BY 1 UNTIL COUNTER > N
           MULTIPLY FACT BY COUNTER GIVING FACT
       END-PERFORM
       DISPLAY 'Factorial: ' FACT
       STOP RUN.

Calculates factorial of 5 using a loop.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. FibonacciProgram.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 N      PIC 9(2) VALUE 10.
       01 A      PIC 9(5) VALUE 0.
       01 B      PIC 9(5) VALUE 1.
       01 TEMP   PIC 9(5) VALUE 0.
       01 COUNTER PIC 9(2) VALUE 1.

       PROCEDURE DIVISION.
       DISPLAY A
       PERFORM VARYING COUNTER FROM 2 BY 1 UNTIL COUNTER > N
           ADD A TO B GIVING TEMP
           DISPLAY B
           MOVE B TO A
           MOVE TEMP TO B
       END-PERFORM
       STOP RUN.

Generates first 10 Fibonacci numbers.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. ArraySum.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 NUMBERS.
          05 NUM PIC 9(2) OCCURS 5 TIMES VALUE 1 2 3 4 5.
       01 SUM PIC 9(3) VALUE 0.
       01 INDEX PIC 9(2) VALUE 1.

       PROCEDURE DIVISION.
       PERFORM VARYING INDEX FROM 1 BY 1 UNTIL INDEX > 5
           ADD NUM (INDEX) TO SUM
       END-PERFORM
       DISPLAY 'Sum: ' SUM
       STOP RUN.

Sum elements of an array.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. MaxProgram.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 A   PIC 9(4) VALUE 7.
       01 B   PIC 9(4) VALUE 10.
       01 MAX PIC 9(4) VALUE 0.

       PROCEDURE DIVISION.
       IF A > B THEN
           MOVE A TO MAX
       ELSE
           MOVE B TO MAX
       END-IF
       DISPLAY 'Max: ' MAX
       STOP RUN.

Finds the maximum of two numbers.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. ReverseString.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 STR PIC X(10) VALUE 'HELLO'.
       01 REV PIC X(10).
       01 INDEX1 PIC 9(2) VALUE 5.
       01 INDEX2 PIC 9(2) VALUE 1.

       PROCEDURE DIVISION.
       PERFORM VARYING INDEX2 FROM 1 BY 1 UNTIL INDEX2 > 5
           MOVE STR (INDEX1:1) TO REV (INDEX2:1)
           SUBTRACT 1 FROM INDEX1
       END-PERFORM
       DISPLAY 'Reversed: ' REV
       STOP RUN.

Reverses a string and displays it.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. EvenNumbers.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 NUMS.
          05 NUM PIC 9(2) OCCURS 10 TIMES VALUE 1 2 3 4 5 6 7 8 9 10.
       01 INDEX PIC 9(2) VALUE 1.

       PROCEDURE DIVISION.
       PERFORM VARYING INDEX FROM 1 BY 1 UNTIL INDEX > 10
           IF NUM (INDEX) MOD 2 = 0 THEN
               DISPLAY NUM (INDEX)
           END-IF
       END-PERFORM
       STOP RUN.

Displays even numbers from an array.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. ConcatStrings.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 STR1 PIC X(5) VALUE 'HELLO'.
       01 STR2 PIC X(5) VALUE 'WORLD'.
       01 RESULT PIC X(10).

       PROCEDURE DIVISION.
       STRING STR1 DELIMITED BY SPACE
              STR2 DELIMITED BY SPACE
              INTO RESULT
       END-STRING
       DISPLAY 'Concatenated: ' RESULT
       STOP RUN.

Concatenates two strings and displays result.