Python is one of the most dynamic programming languages. For its versatility, it is one most used programming languages.
When we are working in Python, there are many times when we need to exit the program before the interpreter. By using the Python Exit in-built function, the program will get outautomatically. In Python, we do not have the Python Exit function alone. There are other techniques in Python for exiting a program, i.e. quit( ), sys.exit ( ) and os._exit( ).
Simple code execution allows the interpreter to reach the end of the script, and then it exits from the program.
In this article, we will learn four different techniques techniques that are used as Python Exit Functions. There will be example code block with output for better understanding.
Table of Contents
Python Exit Functions
When we run a Python program, the code runs in one Python file from the very start to the end. The program exits when it comes to the end of that file. But we can exit code explicitly with Python built-in exit functions.
Let’s learn each Python Exit function one by one.
1. Python exit( ) Function
- The Exit function in Python is only used with the site.py module. But we donot need to import sys module as it is already present in Python library.
- This is the reason we can not use the exit( ) function in a production environment. The production code is the code for the audience to be used in a real-world environment.
- The exit( ) function works with the interpreter only.
- It gives a message when used with the print statement in output of print as it uses SystemExit Exception type and no any Stack Traceback.
Example
evens = [80, 40, 60, 20, 10]
for number in evens:
if number < 20:
print(number,"not allowed")
exit()
else:
print(number,"allowed")
Output
2. Python quit( ) Function
- Quit( ) and exit( ) are said to be synonym functions as they are made to make Python more user-friendly.
- Quit( ) is also used in the site.py module and does not work in a production environment.
- The quit function gives a message on print because of the SystemExit exception raised.
Example
for x in range(2,8):
print(x+3)
quit()
Output
3. Python sys.exit( ) Function
- This function also works like previous ones as it is a part of the sys module of Python. But it is not dependent on the site module.
- Unlike previous functions, sys.exit( ) works in real-world and production code as it is a sys module function available everywhere.
- This function controls the terminal when we work with big files.
- We can pass optional argument in this sys.exit( ) in the form of an integer or any other type of object.
Example
import sys
year = 2016
if year < 2018:
sys.exit("Not Valid")
else:
print("Valid")
Output
4. Python os._exit( ) Function
- os._exit( ) is part of the Python os module. We can see it working in the production environment of Python.
- os._exit( ) exits the process with the specified status immediately.
- This function does not call stdio buffers, cleanup functions and handlers or flushing, etc.
- This statement is not a decent method as it is never a return statement to exit the Python program.
- Primarily, this function is intended to use for killing a child process running.
Example
import os
for x in range(10):
if x == 7:
print(exit)
os._exit(0)
print(x)
Output
Conclusion:
The Python Exit functions are helpful when we don’t want the interpreter to reach the end of the program, and we want to exit beforehand. In the above Python Exit functions, the most preferred method is sys. exit( ) logically. The functions exit( ) and quit( ) are unsuitable for the production environment, and os._exit covers exceptional cases only for immediate exits. In the end, the decision is yours; so that you can decide according to your preferences. I hope the examples are helpful in understanding different Python Exit techniques.
