CodeToLive

Exception Handling in Python

Exception handling in Python allows you to handle errors gracefully and prevent your program from crashing.

Try-Except Block

Use the try and except blocks to catch and handle exceptions.

try:
    result = 10 / 0
except ZeroDivisionError:
    print("Cannot divide by zero!")
      

Handling Multiple Exceptions

You can handle multiple exceptions by specifying multiple except blocks.

try:
    num = int(input("Enter a number: "))
    result = 10 / num
except ValueError:
    print("Invalid input! Please enter a number.")
except ZeroDivisionError:
    print("Cannot divide by zero!")
      

Else Clause

The else clause is executed if no exceptions occur in the try block.

try:
    num = int(input("Enter a number: "))
    result = 10 / num
except ZeroDivisionError:
    print("Cannot divide by zero!")
else:
    print(f"Result: {result}")
      

Finally Block

The finally block is executed regardless of whether an exception occurs.

try:
    file = open("example.txt", "r")
    content = file.read()
    print(content)
except FileNotFoundError:
    print("File not found!")
finally:
    file.close()
    print("File closed.")
      

Custom Exceptions

You can define custom exceptions by creating a new class that inherits from Exception.

class CustomError(Exception):
    pass

try:
    raise CustomError("This is a custom error")
except CustomError as e:
    print(e)
      

Exception Chaining

Exception chaining allows you to raise a new exception while preserving the original exception.

try:
    result = 10 / 0
except ZeroDivisionError as e:
    raise ValueError("Invalid operation") from e
      

Raising Exceptions

You can raise exceptions manually using the raise keyword.

def check_age(age):
    if age < 0:
        raise ValueError("Age cannot be negative.")
    return age

try:
    check_age(-5)
except ValueError as e:
    print(e)