Python’s try-except blocks are used to catch and handle errors gracefully without crashing your program. They allow your code to continue running even when unexpected situations occur, such as dividing by zero, opening a missing file, or converting invalid input types.

In this post, we'll explore how try-except works, different ways to use it, and real-world examples to help you write more reliable Python programs.

1. Basic Structure of try-except

try:
    # code that might raise an error
except SomeError:
    # code that runs if the error occurs

Example 1: Division by Zero

try:
    result = 10 / 0
except ZeroDivisionError:
    print("You can't divide by zero!")

This prevents your program from crashing and displays a custom error message.

2. Catching Specific Exceptions

try:
    number = int("abc")
except ValueError:
    print("Please enter a valid number.")

This handles only ValueError and lets other errors raise normally.

3. Catching Multiple Exceptions

Example 2: Handling More Than One Error Type

try:
    x = int("abc")
    y = 10 / 0
except ValueError:
    print("Conversion error.")
except ZeroDivisionError:
    print("Math error.")

4. Using a Generic Exception Handler

When you're unsure what error might occur, catch all exceptions using Exception.

Example 3: Generic Catch

try:
    risky_code = open("missing.txt")
except Exception as e:
    print("Something went wrong:", e)

Note: Use this sparingly. It can mask real issues during debugging.

5. try-except-else Structure

else runs only if no exceptions were raised in the try block.

Example 4:

try:
    value = int("123")
except ValueError:
    print("Invalid number.")
else:
    print("Conversion successful:", value)

6. try-except-finally Structure

finally always runs, whether or not there was an exception.

Example 5:

try:
    file = open("example.txt", "r")
except FileNotFoundError:
    print("File not found.")
finally:
    print("This block always runs.")

7. Nesting Try-Except Blocks

Example 6: Handling Errors at Different Levels

try:
    number = int(input("Enter a number: "))
    try:
        result = 100 / number
    except ZeroDivisionError:
        print("Can't divide by zero.")
except ValueError:
    print("Invalid input.")

8. Raising Custom Errors with Try-Except

Example 7:

try:
    age = -5
    if age < 0:
        raise ValueError("Age cannot be negative.")
except ValueError as ve:
    print("Error:", ve)

9. Summary Table

10. Final Thoughts

The try-except block is a powerful tool that lets you handle runtime errors without crashing your program. By using it properly, you can build applications that are more stable, user-friendly, and easier to debug. Always handle known exceptions specifically, and reserve generic exception handling for unknown or unexpected errors.