#print("EOFError: You didn't enter anything!")
Error checking pytho iconsole input code#
We can add a finally statement that lets us execute code after we do our error handling in catch $ nano input.py The try statement tells Python to try the code inside the statement and to pass any exception to the except statement before exiting. Print("EOFError: You didn't enter anything!") What if we get bad input from a user? Let’s look back at our input.py script, and add the ability to handle bad input from the user ( CTRL+D to pass an EOF character) $ nano input.py If we don’t want to import extra modules, we can do what exit(), quit() and sys.exit() are doing behind the scenes and raise SystemExit $ python3 Notice that we need to explicitly import a module to call exit(), this might seem like its not an improvement, but it guarantees that the necessary module is loaded because it’s not a good assumption site will be loaded at runtime. For our programs, we should use something like sys.exit $ python3 Neither quit() nor exit() are considered good practice, as they both require the site module, which is meant to be used for interactive interpreters and not in programs. Type "help", "copyright", "credits" or "license" for more information.Įxit() has the same functionality as it is an alias for quit() $ python3 When Python reaches the EOF condition at the same time that it has executed all the code without throwing any exceptions, which is one way Python may exit “gracefully.” The EOFError exception tells us that the Python interpreter hit the end of file (EOF) condition before it finished executing the code, as the user entered no input data. Now, press CTRL+X to save and exit the nano window and in your shell type: $ python3 input.pyĪnd press CTRL+D to terminate the program while it’s waiting for user input Traceback (most recent call last): Then paste the following into the shell by right-clicking on the PowerShell window name=input("Don't type anything!\n") To demonstrate, let’s try to get user input and interrupt the interpreter in the middle of execution!įirst, from your bash terminal in your PowerShell open a new file called “input.py”: $ nano input.py
When the Python interpreter reaches the end of the file (EOF), it notices that it can’t read any more data from the source, whether that be the user’s input through an IDE or reading from a file. The way Python executes a code block makes it execute each line in order, checking dependencies to import, reading definitions and classes to store in memory, and executing pieces of code in order allowing for loops and calls back to the defined definitions and classes. Python Dictionaries Access Items Change Items Add Items Remove Items Loop Dictionaries Copy Dictionaries Nested Dictionaries Dictionary Methods Dictionary Exercise Python If.Else Python While Loops Python For Loops Python Functions Python Lambda Python Arrays Python Classes/Objects Python Inheritance Python Iterators Python Scope Python Modules Python Dates Python Math Python JSON Python RegEx Python PIP Python Try.Why does Python automatically exit a script when it’s done?
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