Common exception types in Python

Introduction

Exceptions help us find and handle errors in our programs so they don't crash unexpectedly.

When reading a file that might not exist.

When dividing numbers and the divisor could be zero.

When converting user input to a number that might be invalid.

When accessing a list item that might be out of range.

When working with keys in a dictionary that might not be present.

Syntax

Python

try:
    # code that might cause an error
except ExceptionType:
    # code to handle the error

Replace ExceptionType with the specific error you want to catch.

You can catch multiple exceptions by listing them in parentheses.

Examples

This catches the error when dividing by zero.

Python

try:
    x = 1 / 0
except ZeroDivisionError:
    print("Cannot divide by zero!")

This catches the error when converting a string that is not a number.

Python

try:
    value = int('abc')
except ValueError:
    print("Invalid number!")

This catches the error when accessing a list index that does not exist.

Python

try:
    my_list = [1, 2, 3]
    print(my_list[5])
except IndexError:
    print("Index is out of range!")

Sample Program

This program asks the user for a number, then divides 10 by that number. It handles errors if the input is not a number or if the number is zero.

Python

try:
    number = int(input("Enter a number: "))
    result = 10 / number
    print(f"10 divided by {number} is {result}")
except ValueError:
    print("Oops! That is not a valid number.")
except ZeroDivisionError:
    print("Oops! Cannot divide by zero.")

Important Notes

Always catch specific exceptions instead of a general Exception to avoid hiding bugs.

You can use multiple except blocks to handle different errors separately.

Use try-except to keep your program running smoothly even when errors happen.

Summary

Exceptions help catch and handle errors in your code.

Common exceptions include ValueError, ZeroDivisionError, and IndexError.

Use try-except blocks to manage errors and keep your program running.