Errors and Exceptions - in - Python.pptx
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In Python, errors and exceptions are mechanisms to handle unexpected events or conditions that arise during the execution of a program. Understanding these concepts is crucial for writing robust and error-free code. Errors are issues that occur due to incorrect code or logic. They prevent the program from running correctly. Common types of errors include: A runtime error is an error that occurs due to an illegal operation in the program. It is caught during the program run. A logical error is an error that occurs due to a fault in the algorithm of the program. It is not caught, either at compile or runtime, but causes an issue.
![COMMON BUILT-IN EXCEPTIONS
Python has many built-in exceptions for specific issues:
ZeroDivisionError: Dividing by zero (e.g., 10 / 0).
TypeError: Wrong data type (e.g., "2" + 3).
NameError: Using undefined variable (e.g., print(x) before defining x).
FileNotFoundError: Opening a missing file (e.g., open("data.txt")).
IndexError: Accessing invalid list index (e.g., lst = [1, 2]; lst[5]).
Check Them: Use dir(__builtins__) to see all built-in exceptions.](https://image.slidesharecdn.com/errorsandexceptions-250421182350-30f33fcd/85/Errors-and-Exceptions-in-Python-pptx-4-320.jpg)
Errors and Exceptions - in - Python.pptx
- 2. WHAT ARE ERRORS AND EXCEPTIONS? Errors: Mistakes in code that stop it from running or executing. Syntax Errors: Wrong code structure (e.g., missing colon). Exceptions: Special errors Python can handle during runtime. Problems during execution (e.g., dividing by zero). Example: Trying to open a missing file raises a FileNotFoundError. Why Care? Handling exceptions makes programs reliable and user-friendly.
- 3. TYPES OF ERRORS Syntax Errors: Code breaks Python’s rules. Caused by incorrect language syntax (parsing errors) print("Hello) # Missing quote → SyntaxError Exceptions: Hard to spot; Happen when code runs, at runtime after passing syntax checks. x = 10 / 0 # Division by zero → ZeroDivisionError
- 4. COMMON BUILT-IN EXCEPTIONS Python has many built-in exceptions for specific issues: ZeroDivisionError: Dividing by zero (e.g., 10 / 0). TypeError: Wrong data type (e.g., "2" + 3). NameError: Using undefined variable (e.g., print(x) before defining x). FileNotFoundError: Opening a missing file (e.g., open("data.txt")). IndexError: Accessing invalid list index (e.g., lst = [1, 2]; lst[5]). Check Them: Use dir(__builtins__) to see all built-in exceptions.
- 5. HANDLING EXCEPTIONS WITH TRY EXCEPT Use try and except to catch and handle exceptions: try: num = int(input("Enter a number: ")) result = 10 / num print("Result:", result) except ZeroDivisionError: print("Error: Cannot divide by zero!") except ValueError: print("Error: Please enter a valid number!") How It Works: try: Run risky code. except: Handle specific errors. else: Runs if no error (e.g., print("Success!")). finally: Always runs (e.g., to close a file). Example Output: Input 0 → "Error: Cannot divide by zero!" Input "abc" → "Error: Please enter a valid number!"
- 6. UNDERSTANDING TRY-EXCEPT-ELSE-FINALLY try Block This is where you put your code that might cause an error. If an error occurs, Python jumps to the except block. except Block This is where you handle the error. You can specify the type of error or catch any exception. else Block (optional) This runs only if no exception occurs in the try block. It helps separate normal code from exception handling. finally Block (optional) This block always runs—whether an exception occurs or not. It’s used for cleanup tasks like closing a file or releasing resources.
- 7. try: num = int(input("Enter a number: ")) result = 10 / num # Might cause ZeroDivisionError except ZeroDivisionError: print("Oops! Division by zero is not allowed.") except ValueError: print("Invalid input! Please enter a valid number.") else: print(f"Success! Your result is {result}") finally: print("Execution complete. Thanks for using our program!") How It Works: If the user enters “0”, it triggers ‘ZeroDivisionError’, which is handled “except”. If they enter “abc”, it triggers ‘ValueEror’, which is also handled If they enter “5”, the ‘else’ block runs smoothly with the calculation. Regardless of what happens, the ‘finally’ block runs every time This helps prevent our program from crashing unexpectedly.