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How to end a Python program

When you are writing your Python program, knowing how to gracefully terminate your code is crucial for proper execution and resource management. Whether you need to exit the program under certain conditions, handle errors, or provide an explicit termination point, Python offers multiple approaches to end a program effectively. In this blog post, we will explore different methods for terminating a Python program, allowing you to maintain control and ensure desired program behavior.

Method 1: Do nothing

In Python, a program naturally terminates when it reaches the end of the script. In other words, you can allow the program to exit gracefully by ensuring it completes all the necessary operations. Here's an example:
The output is:
By allowing the program to reach its logical conclusion, it will terminate without the need for explicit termination statements. This method is suitable when your program has a defined set of tasks to execute and doesn't require any early termination or exceptional handling.

Method 2: Use the sys.exit() function

The sys module in Python provides the exit() function, allowing you to exit the program gracefully. Here's an example:
Note that in this program we print the starting message but then call the sys.exit() function before the second print line.
If you run this program in an environment like repl, we will obtain the following output:
In this case, the sys.exit() call stops the program's execution immediately. It's important to note that any code following the sys.exit() statement will not be executed. This approach is useful when you need to halt the program execution at a specific point or in response to certain conditions (so the sys.exit() function will be enveloped inside an if statement perhaps).

Method 3: Raise a SystemExit exception

The third option, to be used in very serious circumstances, involves the SystemExit exception that you can raise to terminate a program. Here's an example:
The output will be similar to the above:
Thus, just like sys.exit(), raising a SystemExit exception immediately terminates the program and prevents any code following the exception from executing. You can use this method to handle specific scenarios where an exception-based termination is preferred.
To summarize, in this blogpost, we have explored different methods to end a Python program gracefully. By utilizing the sys.exit() function, raising a SystemExit exception, or allowing the program to reach the end naturally, you can control program termination according to your specific requirements. Understanding these techniques empowers you to handle program exits effectively, ensuring proper resource management and desired program behavior. Remember to choose the method that best aligns with your program's logic and termination needs.
If you liked this blogpost, checkout our blogpost on how to add delays to your Python program.
Interested in more things Python? Checkout our post on Python queues. Also see our blogpost on Python's enumerate() capability. Also if you like Python+math content, see our blogpost on Magic Squares. Finally, master the Python print function!
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