Exception handling is a critical aspect of writing robust Python programs. It allows you to manage errors gracefully and maintain the normal flow of your application.
Understanding Exceptions
An exception is an error that occurs during the execution of a program. If not handled, it terminates the program.
Basic try-except Block
try:
# Code that may raise an exception
except ExceptionType:
# Code to handle the exception
Example: Handling FileNotFoundError
try:
file = open('nonexistent.txt', 'r')
except FileNotFoundError:
print("File not found.")
Using finally Block
The finally
block executes regardless of whether an exception occurred:
try:
file = open('data.txt', 'r')
except Exception as e:
print(e)
finally:
print("Execution complete.")
Raising Exceptions
You can raise exceptions using the raise
keyword:
if age < 0:
raise ValueError("Age cannot be negative.")
Conclusion
Exception handling ensures that your Python programs can handle unexpected situations without crashing. Proper use of try-except blocks enhances the reliability of your code.