Testing online COBOL environments

I often use web-based environments, to test the syntax of particular statements in programing languages. As a fun challenge, I decided to see if I could find a web-based environment to test COBOL code. I was expecting this to be an impossible quest because; “why would you?” 😊

After trying a couple of sites, I landed on tutorials point’s web site:
Tutorialspoint online COBOL compiler

Using this website, I was able to write a simple COBOL program to reverse a string. Some of the key concepts used are
a. PERFORM VARYING
b. One dimensional table
c. Reference modification, aka COBOL speak for substring

Below is a screen shot of the web interface. The source code is displayed in the left panel. When you press the execute button, the right panel is a terminal that accepts input and displays output.

Occasionally the web interface displays its true unix/php identity with a message such as:

This can be remediated by putting the string in quotes as shown below:

The complete source code in text is below:

IDENTIFICATION DIVISION.
PROGRAM-ID. REVERSESTRING.

DATA DIVISION.

WORKING-STORAGE SECTION.
01  GENERAL-VARIABLES.
    05  WS-ORIGINAL-TXT           PIC X(100).
    05  WS-REVERSE-TXT-TABLE.
        10  WS-REVERSE-TXT-ITEM   PIC X(1) OCCURS 100 TIMES.
    05  WS-I                      PIC S9(3)  USAGE IS COMP-3 VALUE 0.
    05  WS-J                      PIC S9(3)  USAGE IS COMP-3 VALUE 0.
    05  WS-TEMP                   PIC X(01).
    05  WS-ORIG-TXT-LEN           PIC S9(3)  USAGE IS COMP-3.

PROCEDURE DIVISION.
    DISPLAY "Enter a string to reverse: "
    ACCEPT WS-ORIGINAL-TXT

    PERFORM VARYING WS-I FROM 100 BY -1 UNTIL ( WS-I = 1 OR WS-TEMP <> ' ')
            MOVE WS-ORIGINAL-TXT(WS-I:1) TO WS-TEMP
    END-PERFORM
    COMPUTE  WS-ORIG-TXT-LEN = WS-I + 1
    DISPLAY "You entered    : " WS-ORIGINAL-TXT(1:WS-ORIG-TXT-LEN)

    PERFORM VARYING WS-I FROM WS-ORIG-TXT-LEN BY -1 UNTIL (WS-I = 0)
            COMPUTE WS-J = WS-J + 1
            MOVE WS-ORIGINAL-TXT(WS-I:1) TO  WS-REVERSE-TXT-ITEM(WS-J)
    END-PERFORM
    
    DISPLAY "Reverse string : " WS-REVERSE-TXT-TABLE
    
    STOP RUN.