What is error handling in Python and how to implement it?

Question

Jayant Kumar · Accepted Answer

Table of Contants
Introduction
Error handling in Python is a crucial aspect of writing reliable programs. It ensures that the program can respond to unexpected events, such as incorrect user input, file read/write issues, or other runtime exceptions. Python provides several built-in mechanisms for managing exceptions using try, except, else, and finally blocks. This guide will explain how to implement error handling in Python effectively, complete with practical examples.
Components of Python Error Handling
Using the try-except Block
The try-except block is the most common way to handle exceptions in Python. The code within the try block is executed, and if an error occurs, the control moves to the except block to handle it.
try:
    num = int(input("Enter a number: "))
    result = 100 / num
except ZeroDivisionError:
    print("Cannot divide by zero!")
except ValueError:
    print("Invalid input! Please enter a number.")

In this example:

The try block attempts to convert user input into an integer and divide 100 by the entered number.
The except blocks handle specific exceptions like ZeroDivisionError and ValueError.

Handling Multiple Exceptions
In Python, you can handle multiple exceptions in a single except block by using a tuple.
try:
    num = int(input("Enter a number: "))
    result = 100 / num
except (ZeroDivisionError, ValueError) as e:
    print(f"Error occurred: {e}")

By combining exceptions in a tuple, this method simplifies error handling when multiple types of exceptions might occur.
The else and finally Blocks

**else**: The else block runs only if no exceptions are raised in the try block.
**finally**: The finally block always runs, whether an exception is raised or not. It is often used for resource cleanup (e.g., closing files).

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

Practical Examples of Error Handling
Example ; Validating User Input
This example checks if user input is a valid integer and handles errors appropriately.
def get_age():
    try:
        age = int(input("Enter your age: "))
    except ValueError:
        print("Invalid input. Please enter a valid number.")
        return None
    else:
        print(f"Your age is {age}.")
        return age

Example : Custom Exception Handling
You can create custom exceptions by inheriting from Python's Exception class.
class CustomError(Exception):
    pass

try:
    raise CustomError("This is a custom error.")
except CustomError as e:
    print(f"Caught a custom error: {e}")

Conclusion
Error handling in Python is vital for building robust applications that can gracefully handle unexpected scenarios. Using try-except, else, and finally blocks, you can ensure that errors are caught and dealt with efficiently. By implementing proper error handling, your code becomes more maintainable and user-friendly.

What is error handling in Python and how to implement it?

Table of Contants

Introduction

Components of Python Error Handling

Using the `try-except` Block

Handling Multiple Exceptions

The `else` and `finally` Blocks

Practical Examples of Error Handling

Example ; Validating User Input

Example : Custom Exception Handling

Conclusion

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