Debugging is a crucial skill for any programmer, and COBOL is no exception. This section will guide you through the process of identifying and fixing errors in your COBOL programs. We will cover various debugging techniques, tools, and best practices to help you become proficient in debugging COBOL code.

1. Types of Errors:

   • Syntax Errors: Mistakes in the code that violate the rules of the COBOL language.
   • Runtime Errors: Errors that occur while the program is running, often due to invalid data or logic errors.
   • Logical Errors: Errors in the program's logic that produce incorrect results.

2. Debugging Tools:

   • COBOL Debuggers: Specialized tools designed to help you step through your code, inspect variables, and identify errors.
   • Compiler Options: Many COBOL compilers offer options to generate additional debugging information.

3. Debugging Techniques:

   • Code Review: Manually inspecting your code to find errors.
   • Print Statements: Adding display statements to output variable values and program flow.
   • Step-by-Step Execution: Using a debugger to execute your program one line at a time.

Let's consider a simple COBOL program that calculates the sum of two numbers. We'll introduce a deliberate error and then debug it.

In this example, the program should display the sum of NUM1 and NUM2. However, let's assume the output is incorrect due to a logical error.

1. Review the Code:

   • Check the ADD statement and the DISPLAY statement for any obvious mistakes.

2. Add Print Statements:

   • Insert DISPLAY statements to print the values of NUM1, NUM2, and RESULT before and after the ADD operation.

3. Run the Program:
   • Execute the program and observe the output.

• Incorrect Data Types: Ensure that the data types of variables are appropriate for the operations being performed.
• Uninitialized Variables: Always initialize variables before using them in calculations.
• Incorrect Logic: Verify that the logic of your program matches the intended functionality.

• IBM Debug Tool: A powerful debugger for COBOL programs running on IBM mainframes.
• Micro Focus COBOL Debugger: A versatile debugger for COBOL programs on various platforms.

• Debugging Information: Use compiler options to include debugging information in the compiled program. For example, in Micro Focus COBOL, you can use the -g option.

1. Modularize Your Code: Break your program into smaller, manageable modules. This makes it easier to isolate and debug errors.
2. Use Meaningful Variable Names: Descriptive variable names make your code easier to read and debug.
3. Comment Your Code: Include comments to explain complex logic and important sections of your code.
4. Test Incrementally: Test your program in small increments to catch errors early.

Debugging is an essential skill for COBOL programmers. By understanding the types of errors, using appropriate debugging tools, and following best practices, you can efficiently identify and fix issues in your COBOL programs. Practice these techniques regularly to become proficient in debugging and ensure the reliability of your COBOL applications.