How To Handle Exceptions (3 Min) In Python | Learn Error & Exception Handling

In this tutorial, you'll learn how to handle exceptions in Python.

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Video Transcript:
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Hi guys, this is Abhi from Gokcedb. In this video, you're going to learn how to handle exceptions in Python. Let's start by looking at the try block on line 3.

I'm accepting the first number as input from the user. On line 5, I'm accepting the second number. Next, I'm using the erase keyword to raise an exception if num2 is equal equal to 7.

On line 8, I'm printing the result of dividing num1 by num2. On line 9, I'm using the accept keyword to catch the 0 division if num2 is equal to zero. Next, let's test this out by inputting the second number as zero.

The reason you see goodbye in the output is that I have a final block where I'm printing goodbye which gets executed every time irrespective of whether there was an exception or not. On line 11, I'm catching a value error in case the number provided is not a numerical value. On line 13, I'm catching keyword interrupt in case the execution of the program is interrupted by the user by pressing the stop button or say by passing CRTL C on the command line.

Line 15, I'm catching all the exceptions that were not caught by the above except blocks. If we go back to line 7, you'll see that I'm using the erase keyword to raise an exception if num2 is equal equal to 7. Let's see what happens when I input 7 as the second number.

Looks like we caught the type error exception in this generic exception block. Note the accept exception block catches all the subclasses of the exception class. If you look at the UML diagram of the zero division error class, you'll see that it inherits from the exception class.

Similarly, value error is also a subclass of the exception class. However, if you look at the UML diagram of keyboard interrupt, you'll notice that it inherits from the base exception class and not the exception class. That's because keyboard interrupt is a system-level exception.

Therefore to catch all the system lever exceptions in addition to regular exceptions you have to define an accept base exception block. Here I commented out except keyboard interrupt block to see if except base exception block catches it. Finally, if we rerun the program and no exception is found then the else block will also get executed.

There you have it. Make sure you like, subscribe, and turn on the notification bell. Until next time.

try:
print("Enter the first number:")
num1 = int(input())
print("Enter the second number:")
num2 = int(input())
if num2 == 7:
raise "Not 7"
print("Here's the result of dividing num1/num2:", num1/num2)
except ZeroDivisionError:
print("ZeroDivisionError: Cannot divide by 0")
except ValueError:
print("ValueError: Can only divide numerical value")
# except KeyboardInterrupt:
# print("KeyboardInterrupt: Execution interrupted by user")
except Exception as e: # catch all subclasses of Exception
print("Caught some other Exception:", e.__class__.__name__)
except BaseException as be: # catch all subclasses of BaseException
print("Caught a system-level exception:", be.__class__.__name__)
else:
print("No exceptions were found")
finally:
print("Goodbye")