Try except and finally in python

In Python, try, except, and finally are used for handling exceptions, which are errors detected during execution. These keywords allow you to gracefully handle errors and execute code regardless of whether an error occurred.

1. try Block

The try block lets you test a block of code for errors.

try:
    # Code that may cause an exception
    result = 10 / 0
    print(result)
except ZeroDivisionError:
    print("You can't divide by zero!")

2. except Block

The except block lets you handle the error.

try:
    # Code that may cause an exception
    result = 10 / 0
    print(result)
except ZeroDivisionError:
    print("You can't divide by zero!")

In this example, the ZeroDivisionError exception is caught and a message is printed instead of the program crashing.

3. finally Block

The finally block lets you execute code, regardless of the result of the try and except blocks.

try:
    # Code that may cause an exception
    result = 10 / 0
    print(result)
except ZeroDivisionError:
    print("You can't divide by zero!")
finally:
    print("This will always be executed.")

Here, the message in the finally block will be printed no matter if an exception occurred or not.

Combined Example

Here’s a more comprehensive example that combines try, except, and finally:

def divide(a, b):
    try:
        result = a / b
    except ZeroDivisionError:
        print("Error: Division by zero is not allowed.")
        result = None
    finally:
        print("Execution complete.")
    return result

# Testing the function
print(divide(10, 2))  # Expected output: 5.0
print(divide(10, 0))  # Expected output: Error message and None

In this example:

• The try block contains the code that may raise an exception.
• The except block handles the specific ZeroDivisionError exception.
• The finally block contains code that will always be executed, whether an exception occurs or not.

Multiple Except Blocks

You can also have multiple except blocks to handle different types of exceptions.

try:
    value = int(input("Enter a number: "))
    result = 10 / value
except ValueError:
    print("Error: Invalid input. Please enter a number.")
except ZeroDivisionError:
    print("Error: Division by zero is not allowed.")
finally:
    print("Execution complete.")

In this case, different exceptions (ValueError and ZeroDivisionError) are handled separately, providing more specific error messages.

Using try, except, and finally helps in making your code more robust and error-tolerant.