Python is a beautiful programming language. It is loved by developers because of its elegant syntax and readability. For this very reason, a lot of developers are choosing python as their first choice for building applications.
In this blog, we will be going to discuss various ways you can use to make your python program exiting. There are various ways in which Python exits a program or loop. Here we will see the important ones:
There are different ways to make your python program exiting, which I will explain in this blog post. The examples are using the PyQt5 toolkit and the Python programming language.
1. sys.exit()
2. raise SystemExit
3. os._exit()
4. quit()
5. exit()
As a programmer, we sometimes forget about the user and what our program does to them. In this post I will be talking about five ways to exit your python program. I will also go over why you should use these methods and why it’s a best practice to always have an exit method in your code.
Let’s get started with the first way to end your program:
Python is a very flexible interpreted language. But, sometimes you will need your program to exit in some condition other than the usual no-error, all-is-well scenario.
Here are 5 ways to make your python program exit:
1. sys.exit(): This will exit the program and return an exit status to the operating system.
2. raise SystemExit: This will exit the program and raise a SystemExit exception.
3. os._exit(): This will terminate the current process immediately without calling any cleanup handlers, flushing stdio buffers, etc. It means that any finally or except clauses in your code will not be executed before exiting the process.
4. Quit keyword: If you want to quit from IDLE, then press CTRL+D or type quit(). But this works only within IDLE and not from command prompt or any other editor for Python programming language.
5. App Exit: In PyQt4 applications, you can use QApplication::exit() method to terminate your application in a clean way.
When writing a Python program, we may want the program to exit in some situations. For example, if your program is downloading an image from internet and the internet connection is lost, we may want to exit the program.
In this blog post I will show how to make your Python program exiting in different ways and explain what exactly happens when you are terminating your programs.
Exiting with exit()
You can use exit() function of Python to exit from a script by passing a value to it. If no value is passed then the default value of zero is considered implying that the script exited successfully.
The following example shows how to use exit() function:
import sys
It is quite common to find yourself in situations where you have to write a program that does not have a user interface. In these scenarios, sometimes we want the program to exit after it is done doing its job. Exiting a python program is simple and easy, it can be done by creating a system variable called EXIT_CODE.
Creating the variable is super simple, just do this:
EXIT_CODE = 0
This creates an integer variable with the value of 0. This can be changed to whatever number you want. The only important thing is that it exists, because the system looks for this variable when the program exits. If it finds the variable, it will use its value as the exit code for your program. If not, it will default to 1 (general error).
In order to make use of this variable, all you need to do is add this line at the end of your code:
sys.exit(EXIT_CODE)
This command will exit your Python script with either the EXIT_CODE value or 1 if no such variable exists in your code.
The simplest way of exiting a program is by using the sys.exit() method. This method takes in an integer value, 0 to 255, where 0 means that the program has successfully completed and any other number means that there was an error during execution.
The second way of exiting a program is by raising the SystemExit exception. This exception can be raised with or without a value parameter. If you raise this exception with no parameter, it behaves just like sys.exit(), i.e., it exits the program without any error message. But if you raise this exception with a value parameter, then this parameter would be converted to a string and printed as an error message before exiting the program.
The third way of exiting a program is by using the exit() function from the built-in module os. This function also accepts an integer value in the range 0-255, but unlike sys.exit(), it does not have to be imported from any module and is available directly after Python starts up.
The fourth way of exiting a program is by raising the EOFError exception. Since this exception represents end-of-file, it can be raised like this:
raise EOFError
Just like SystemExit, this exception also has no default error message if