Handling Errors in Python: Try, Except, and Best Practices

Errors are an inevitable part of programming. Python provides the try-except block to handle exceptions effectively, preventing programs from crashing unexpectedly.

Why Handle Errors?

• Prevents program crashes: Allows the program to continue running despite errors.
• Improves user experience: Provides meaningful error messages.
• Enhances debugging: Helps track and fix bugs efficiently.

Using Try-Except Blocks

A try block is used to wrap code that might raise an exception. The except block catches and handles the error.

try:
    x = 10 / 0  # This will raise a ZeroDivisionError
except ZeroDivisionError:
    print("Error: Cannot divide by zero!")

Handling Multiple Exceptions

You can handle multiple exceptions by specifying multiple except blocks.

try:
    num = int("abc")  # This will raise a ValueError
except ZeroDivisionError:
    print("Error: Division by zero!")
except ValueError:
    print("Error: Invalid input!")

Using the Exception Object

You can capture exception details using as.

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

The Finally Block

The finally block executes no matter what, making it useful for cleanup tasks.

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

Raising Exceptions

Use the raise keyword to trigger exceptions manually.

def check_age(age):
    if age < 18:
        raise ValueError("Age must be 18 or older.")
    print("Access granted.")

check_age(16)  # Raises ValueError

Best Practices for Error Handling

• Be specific with exceptions: Catch only the exceptions you expect.
• Avoid bare except: Always specify an exception type.
• Use logging instead of print: Helps in debugging.
• Close resources properly: Use finally or with statements.

Conclusion

Handling errors properly improves code reliability and user experience. Using try-except correctly ensures your programs run smoothly even in unexpected situations.

Quiz Questions

1. What is the purpose of a try-except block in Python?
2. How can you handle multiple exceptions in a single block?
3. What does the finally block do in exception handling?
4. How do you manually raise an exception in Python?
5. Why should you avoid using a bare except statement?