Python Try Except

Python Try-Except (Exception Handling) Tutorial

In Python, errors that occur during program execution are called exceptions. If exceptions are not handled, they stop the program. To prevent this, we use try-except blocks to handle errors gracefully.

1. Basic Try-Except Example

try:
    x = 10 / 0  # Division by zero
except ZeroDivisionError:
    print("Error: Cannot divide by zero!")

✅ Explanation: If an error occurs inside try, the except block executes instead of crashing the program.

2. Handling Multiple Exceptions

try:
    num = int(input("Enter a number: "))  # Input may not be an integer
    result = 10 / num  # Might cause division by zero
except ValueError:
    print("Error: Invalid input! Please enter a number.")
except ZeroDivisionError:
    print("Error: Cannot divide by zero!")

✅ Explanation:

ValueError occurs if input is not a number.
ZeroDivisionError occurs if input is 0.

3. Using a Generic Exception

try:
    print(10 / 0)
except Exception as e:
    print("Error:", e)

✅ Explanation: Exception as e catches any error and prints its message.

4. Using Else and Finally

try:
    num = int(input("Enter a number: "))
    print("You entered:", num)
except ValueError:
    print("Error: Invalid input!")
else:
    print("No errors occurred.")  # Runs if no error occurs
finally:
    print("Execution completed.")  # Always runs

✅ Explanation:

else: Runs only if no exception occurs.
finally: Runs whether an error occurs or not (useful for cleanup).

5. Raising Exceptions Manually

age = int(input("Enter your age: "))
if age < 18:
    raise ValueError("You must be 18 or older!")

✅ Explanation: raise lets us trigger custom errors.

Conclusion

Using try-except, we can prevent program crashes, improve user experience, and ensure smooth execution.

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