What happens when an exception is raised and the program does not handle it with a try except statement?
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By Eric Carb Show Exception Control Flow - Try, Except, Else, Finally Exceptions in Python are objects that represent errors. Exceptions can be raised in many ways, such as passing invalid arguments to functions (“Boo” + 7), performing certain illegal operations (12 / 0) or even explicitly (raise TypeError). By default, exceptions stop Python programs and print a Traceback to the console with information about the exception and how it was raised. However, the try statement exists to give control flow to exceptions so that you can prevent your program from crashing and even use exception objects to your advantage. This is commonly referred to as “catching” an exception. The try statement looks like this: try: The code with the exception that you want to catch. If an exception is raised, control flow leaves this block immediately and goes to the except block except [(Exception[, Exception])] [as VAR]: This code is executed only if an exception was raised in the try block. Code executed in this block is just like normal code: if there is an exception, it will not be automatically caught (and probably stop the program). You can optionally name specific types of exceptions in the except statements, in which case the block will only be executed if one of the named exceptions was the one raised in try. When naming multiple exceptions, use a tuple. It is legal to have multiple except statements, each of which names different types of exceptions. If no exceptions are named in the except statement, it will catch all exceptions; useful to put after except statements that name exceptions. Including the as expression with the except statement allows you to store the exception object raised in the try block in a variable and use it within this block. To store an exception in a variable when none are named, name “Exception” instead (i.e. except Exception as e). Only one variable can be listed after as. This block is required (even if all it has is pass). [else:] This code is executed only if no exceptions were raised in the try block. Code executed in this block is just like normal code: if there is an exception, it will not be automatically caught (and probably stop the program). Notice that if the else block is executed, then the except block is not, and vice versa. This block is optional. [finally:] This code always executes after the other blocks, even if there was an uncaught exception (that didn’t cause a crash, obviously) or a return statement in one of the other blocks. Code executed in this block is just like normal code: if there is an exception, it will not be automatically caught (and probably stop the program). This block is also optional. Examples:
* This is what the ZeroDivisionError object looks like when you print it ** Full traceback message (the red text) too large to display What type of exception does a program raise when it tries to open a nonexistent file?For example, trying to open a nonexistent file triggers a type of exception called an IOError … … while an out-of-bounds index to a list triggers an IndexError .
What happens if your program does not catch an exception?What happens if an exception is not caught? If an exception is not caught (with a catch block), the runtime system will abort the program (i.e. crash) and an exception message will print to the console.
What happens if an exception is raised in the program?When an exception is raised, no further statements in the current block of code are executed.
What will happen if an exception occurs but is not handled by the program in Python?If any exception occurs, but the except clause within the code doesn't handle it, it is passed on to the outer try statements. If the exception is left unhandled, then the execution stops.
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