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Exception Handling

Exception handling is a mechanism in Python to handle runtime errors, ensuring that your program can deal with unexpected events gracefully.

 

 

1. Basic Exception Handling

The try and except blocks are used to handle exceptions.

Syntax:

try:
   # Code that may raise an exception
except SomeException as e:
   # Code that runs if the exception occurs
   print(f"An error occurred: {e}")
 

Example:

try:
   result = 10 / 0
except ZeroDivisionError as e:
   print(f"Error: {e}")
 

 

 

2. Handling Multiple Exceptions

You can handle multiple exceptions by specifying them in a tuple.

Example:

try:
   result = 10 / 0
except (ZeroDivisionError, TypeError) as e:
   print(f"Error: {e}")
 

 

3. The else Block

The else block runs if no exceptions are raised in the try block.

Example:

try:
   result = 10 / 2
except ZeroDivisionError as e:
   print(f"Error: {e}")
else:
   print(f"Result: {result}")
 

 

4. The finally Block

The finally block always runs, regardless of whether an exception occurred. It is typically used for cleanup actions.

Example:

try:
   file = open('example.txt', 'r')
   content = file.read()
except FileNotFoundError as e:
   print(f"Error: {e}")
finally:
   file.close()
   print("File closed.")
 

 

5. Raising Exceptions

You can raise exceptions using the raise keyword.

Example:

def divide(a, b):
   if b == 0:
       raise ValueError("Cannot divide by zero")
   return a / b
try:
   result = divide(10, 0)
except ValueError as e:
   print(f"Error: {e}")
 

 

6. Custom Exceptions

You can define your own exceptions by creating a class that inherits from the built-in Exception class.

Example:

class CustomError(Exception):
   pass
def check_value(value):
   if value < 0:
       raise CustomError("Value cannot be negative")
try:
   check_value(-1)
except CustomError as e:
   print(f"Error: {e}")
 

 

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