Exception Handling in Python

An exception is an error that occurs during the execution of a program and stops the normal flow of the program.


print(10 / 0)

This causes a ZeroDivisionError because a number cannot be divided by zero.

What is Exception Handling?

Exception handling in Python is a way to handle runtime errors so that the program does not crash and can continue running smoothly.

Python handles exceptions using:

The try block contains code that may cause an error. The except block handles the error if it occurs.


try:
    x = 10 / 0
    print(x)
except:
    print("Error: Cannot divide by zero")

We can handle specific types of errors.


try:
    num = int("abc")
except ValueError:
    print("ValueError: Invalid number")

The else block runs only if no exception occurs.


try:
    a = 10
    b = 2
    print(a / b)
except ZeroDivisionError:
    print("Cannot divide by zero")
else:
    print("Division successful")

The finally block always executes, whether an exception occurs or not.


try:
    file = open("data.txt", "r")
    print(file.read())
except:
    print("File not found")
finally:
    print("Program finished")

We can manually raise an exception using the raise keyword.


age = -5

if age < 0:
    raise ValueError("Age cannot be negative")