Python Error Handling

What is Error Handling in Python?

Error handling in Python lets you gracefully handle unexpected errors during runtime without crashing the program.

Basic Syntax of try, except

try:
    # Code that may raise an exception
    risky_code()
except ExceptionType:
    # Code to run if an exception occurs
    handle_error()

Example: Basic try-except

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

Possible Outputs:

Enter a number: 0
Cannot divide by zero!

Enter a number: abc
Invalid input, enter a number.

Catch All Exceptions

try:
    result = 10 / 0
except Exception as e:
    print("An error occurred:", e)

Output:

An error occurred: division by zero

Use this with caution - it hides specific error types.

finally Block in Python

The finally block runs no matter what, whether an exception is raised or not.

Example:

try:
    file = open("test.txt", "r")
    print(file.read())
except FileNotFoundError:
    print("File not found!")
finally:
    print("Execution complete.")

Output:

File not found!
Execution complete.

Using else with try-except

The else block runs only if no exception was raised.

try:
    print("No errors here!")
except:
    print("Something went wrong.")
else:
    print("Code ran successfully!")

Common Exception Types in Python

Best Practices for Python Exception Handling

• Catch specific exceptions (not just Exception)
• Use finally to close resources (e.g., files, DB connections)
• Avoid bare except: unless absolutely necessary
• Log exceptions for debugging in production apps