finally for cleanup

Context: The finally block is used to execute code regardless of whether an exception was thrown. It is ideal for releasing resources (file handles, database connections, locks). Unlike catch, finally does not handle the exception; it runs after the try and any matching catch, and then the exception continues to propagate.

Usage Example

using System;
using System.IO;

class Program
{
    static void Main()
    {
        FileStream fs = null;
        try
        {
            fs = File.Open("test.txt", FileMode.OpenOrCreate);
            // Simulate an exception
            throw new InvalidOperationException("Something went wrong");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error: {ex.Message}");
        }
        finally
        {
            if (fs != null)
            {
                fs.Dispose();
                Console.WriteLine("FileStream disposed.");
            }
        }
    }
}

Output console

dotnet run
Error: Something went wrong
FileStream disposed.

Important notes

• finally runs even if there is a return in try or catch.
• Do not throw exceptions in finally; they will replace the original exception.
• The using statement provides a cleaner syntax for disposal.

Real-world usage example

Lock release – Using Monitor.Enter and Monitor.Exit in finally ensures the lock is released even if the protected code throws.
See .NET docs on finally.

Related sections

• 12.1 try catch finally
• 12.1.2 Multiple catch blocks