try…except in Python: Mechanism to Handle Errors

Whenever you execute a code, there is always a possibility that something may go wrong because of an error. This could cause a lot of pressure as you have to check each and every line to find the error. These types of events are called exceptions and handling them is known as exception handling.

Exception handling in python is a programming technique that allows you to handle and manage errors or exceptional situations that can occur during the execution of a program and provides a structured approach to deal with these exceptional situations by allowing you to catch and handle specific types of exceptions. It enables you to write code that can respond to errors, recover from them, or perform alternative actions when an exception occurs.

In this article, you are going to learn about try…except statements in Python which are similar to for loop, if…else or while loop statements, that can help you to handle exceptions in Python programs.

In Python, the try...except statement is a powerful tool used for exception handling. By enclosing risky code within the 'try' block and specifying how to handle specific exceptions in corresponding 'except' blocks, you can ensure that your program continues to run smoothly even in the presence of unexpected errors.

The try...except statement provides a way to catch and respond to exceptions, making your code more robust and reliable.

Syntax for try…except in Python:

 >>> try:
 >>>     # Code that might raise an exception
 >>>     # ...
 >>> except ExceptionType1:
 >>>     # Code to handle ExceptionType1
 >>>     # ...
 >>> except ExceptionType2
 >>>     # Code to handle ExceptionType2
 >>>     # …

In this syntax:

• The 'try' block contains the code that you expect might raise an exception.
• The 'except' block(s) follow the 'try' block and specify the type(s) of exceptions to catch and the corresponding code to handle each exception.
• You can have multiple except blocks to handle different types of exceptions.

Working of try...except in Python:

1. The code within the 'try' block is executed one by one.
2. If an exception occurs during the execution of any statement within the 'try' block, the remaining statements within the block are skipped, and the control is transferred to the appropriate 'except' block.
3. The exception is compared with the specified exception types in the 'except' blocks.
4. If the exception matches any of the exception types listed in the 'except' blocks, the corresponding block is executed. This allows you to handle the exception in a customized way.

NOTE: The order of the 'except' blocks is important. Python will match the exception with the first compatible 'except' block encountered, so specific exceptions should be given rather than general ones.

Example Program for try…except in Python:

 >>> try:
 >>>     x = int(input("Enter a number: "))
 >>>     result = 10 / x
 >>>     print("Result:", result)
 >>> except ValueError:
 >>>     print("Invalid input. Please enter a valid number.")
 >>> except ZeroDivisionError:
 >>>     print("Cannot divide by zero.")

In the example above, if the user enters a non-integer value, a ValueError will occur, and the corresponding except block will execute. If the user enters zero, a ZeroDivisionError will occur, and the appropriate except block will execute.

In conclusion, the try...except statement in Python is an essential tool for handling exceptions and ensuring the stability and reliability of your code. It allows you to anticipate and handle exceptional situations, validate user input, recover from errors, and provide meaningful error messages or alternative behaviors.

This is a bit more advanced topic in Python and it is important to practice with this concept one many times to get a hold on it. If you have further questions or doubts, feel free to get in touch with us.