Range Over Built in COBOL

Here we use PERFORM to sum the numbers in an array-like structure.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. RangeExample.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 nums PIC 9(4) OCCURS 3 VALUE 2, 3, 4.
       01 sum PIC 9(4) VALUE 0.
       01 i PIC 9(4).

       PROCEDURE DIVISION.
           PERFORM VARYING i FROM 1 BY 1 UNTIL i > 3
               ADD nums(i) TO sum
           END-PERFORM
           DISPLAY "sum: " sum.

           *> To get the index:
           PERFORM VARYING i FROM 1 BY 1 UNTIL i > 3
               IF nums(i) = 3
                   DISPLAY "index: " (i - 1)
               END-IF
           END-PERFORM.

           *> Using PERFORM to iterate over key/value pairs:

           01 kvs.
              05 kvs1.
                 10 key1 PIC X VALUE 'a'.
                 10 value1 PIC X(10) VALUE 'apple'.
              05 kvs2.
                 10 key2 PIC X VALUE 'b'.
                 10 value2 PIC X(10) VALUE 'banana'.

           PERFORM VARYING i FROM 1 BY 1 UNTIL i > 2
               IF i = 1
                   DISPLAY "a -> apple"
               ELSE
                   DISPLAY "b -> banana"
               END-IF
           END-PERFORM.

           *> Using PERFORM to iterate over keys:
           PERFORM VARYING i FROM 1 BY 1 UNTIL i > 2
               IF i = 1
                   DISPLAY "key: a"
               ELSE
                   DISPLAY "key: b"
               END-IF
           END-PERFORM.

           *> Using PERFORM to iterate over each character in a string:
           01 my-string PIC X(4) VALUE 'go'.
           01 j PIC 9(4).

           PERFORM VARYING j FROM 1 BY 1 UNTIL j > LENGTH OF my-string
               DISPLAY j - 1 " " FUNCTION ORD(my-string(j:1))
           END-PERFORM.

           STOP RUN.

To run this program, save the code into a file named RangeExample.cbl and compile it using a COBOL compiler like GnuCOBOL.

Example usage:

$ cobc -x -o RangeExample RangeExample.cbl
$ ./RangeExample
sum: 9
index: 1
a -> apple
b -> banana
key: a
key: b
0 103
1 111

This example demonstrates how to iterate over different built-in data structures in COBOL. Now that you understand how to use PERFORM for various data structures, you can explore more COBOL features.

Recursion in COBOL

Pointers in COBOL

Learn X By Example

Title here

Range Over Built in COBOL