When to use Finally in real applications?

Finally block is mostly used to dispose the unwanted objects when they are no more required. This is good for performance, otherwise you have to wait for garbage collector to dispose them.

The finally block in C# is used to define a section of code that will always be executed, regardless of whether an exception is thrown or not. It is typically used in real applications for cleanup operations and resource management. Here are some scenarios where you might use the finally block:

Resource Cleanup:When your code uses resources such as file handles, network connections, database connections, or other external resources, it's important to release these resources properly to avoid leaks or other issues.

The finally block ensures that the cleanup code executes, regardless of whether an exception occurs or not.        

Example:

FileStream file = null;
try
{
    file = new FileStream("file.txt", FileMode.Open);
    // Code that operates on the file
}
catch (IOException ex)
{
    // Exception handling
}
finally
{
    // Cleanup code to release the file resource
    file?.Dispose();
}

In this example, the file resource is opened in the try block, and the finally block is used to ensure that the file is properly closed and released, even if an exception is thrown.

Transaction Handling: In scenarios where you need to ensure that certain operations are always performed, regardless of the success or failure of other operations within a transaction, the finally block can be useful. 

You can use the finally block to commit or rollback a transaction, close connections, or perform other necessary actions.

Example:

using (var transaction = new TransactionScope())
{
    try
    {
        // Code that performs transactional operations
        transaction.Complete();
    }
    catch (Exception ex)
    {
        // Exception handling
    }
    finally
    {
        // Code that always executes, regardless of success or failure
        transaction.Dispose();
    }
}

In this example, the TransactionScope is used to manage a transaction. The finally block ensures that the transaction is disposed, allowing for proper cleanup and rollback if necessary.

Logging and Diagnostic Information:
 

The finally block can be used to include logging or diagnostic statements to track the execution flow and provide additional information in case of exceptions or unexpected behavior.

Example: 

try
{
    // Code that may throw an exception
}
catch (Exception ex)
{
    // Exception handling
}
finally
{
    // Logging or diagnostic statements
}

In this example, the finally block can be used to log information about the execution, such as success or failure indicators, performance metrics, or any other relevant diagnostic data.

Overall, the finally block is useful in situations where you need to guarantee that certain code is always executed, regardless of whether an exception occurs or not. It ensures proper resource cleanup, transaction handling, and allows for necessary logging or diagnostic activities.