How do you handle exceptions in Python

In Python, exceptions are handled using a try-except block to gracefully manage errors and prevent program crashes. Here’s how it works:

Basic Syntax:

python

try:
    # Code that might raise an exception
    result = 10 / 0  # Division by zero (will raise ZeroDivisionError)
except ZeroDivisionError:
    # Code to handle the exception
    print("Cannot divide by zero!")

Key Components:

1. try block:

   • Contains the code that might raise an exception.

   • If an exception occurs, the rest of the try block is skipped.

2. except block:

   • Catches and handles specific exceptions (e.g., ValueError, TypeError).

   • You can catch multiple exceptions or use a generic Exception.

3. else block (optional):

   • Runs only if no exceptions occur in the try block.

4. finally block (optional):

   • Always executes, whether an exception occurred or not (e.g., for cleanup like closing files).

Example with All Blocks:

try:
    num = int(input("Enter a number: "))  # Possible ValueError
    result = 10 / num                    # Possible ZeroDivisionError
except ValueError:
    print("Invalid input! Please enter a number.")
except ZeroDivisionError:
    print("Cannot divide by zero!")
else:
    print(f"Result: {result}")  # Runs if no exception
finally:
    print("Execution complete.")  # Always runs

Common Practices:

1. Catch specific exceptions (avoid bare except:):

   python

   except (ValueError, TypeError) as e:  # Catch multiple exceptions
       print(f"Error: {e}")

2. Get the exception details:

   python

   except Exception as e:
       print(f"An error occurred: {e}")

3. Raise custom exceptions:

   python

   if x < 0:
       raise ValueError("Negative values are not allowed!")

4. Use finally for resource cleanup:

   python

   file = open("example.txt", "r")
   try:
       content = file.read()
   finally:
       file.close()  # Ensures the file is always closed

Built-in Exceptions (Common Ones):

• ValueError: Invalid value (e.g., int("abc")).

• TypeError: Incorrect type (e.g., "hello" + 5).

• IndexError: List index out of range.

• KeyError: Dictionary key not found.

• FileNotFoundError: File does not exist.

Why Use Exception Handling?

• Prevents abrupt program termination.

• Improves debugging with meaningful error messages.

• Ensures resources are released properly (e.g., files, connections)