Python try keyword

The try keyword in Python is used in exception handling to test a block of code for errors. If an exception occurs, the control is passed to the corresponding except block, allowing the program to handle errors gracefully and avoid crashes.

Example 

try:

    result = 10 / 0  # This will raise a ZeroDivisionError

except ZeroDivisionError:

    print("You can't divide by zero!")

Output:

You can't divide by zero!

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Syntax

try:

    # Code that might raise an exception

except ExceptionType:

    # Code to handle the exception

else:

    # Optional: Code to execute if no exception occurs

finally:

    # Optional: Code that always executes, regardless of exceptions

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Why Use try?

1. Error Prevention: Allows you to anticipate and handle potential errors during runtime.
2. Graceful Handling: Prevents program crashes by providing alternative actions when an error occurs.
3. Maintain Flow: Ensures that the program continues executing even if an exception arises.
4. Code Debugging: Identifies where exceptions are likely to occur for better debugging.

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Common Examples

1. Basic Try-Except Block

try:

    number = int(input("Enter a number: "))

    print(f"You entered {number}")

except ValueError:

    print("That's not a valid number!")

Input/Output:

Enter a number: hello

That's not a valid number!

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2. Handling Multiple Exceptions

try:

    num = int(input("Enter a number: "))

    result = 10 / num

except ValueError:

    print("Invalid input! Please enter a valid number.")

except ZeroDivisionError:

    print("Division by zero is not allowed.")

Input/Output:

Enter a number: 0

Division by zero is not allowed.

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3. Using else

try:

    num = int(input("Enter a positive number: "))

except ValueError:

    print("Invalid input!")

else:

    print(f"You entered: {num}")

Input/Output:

Enter a positive number: 10

You entered: 10

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4. Using finally

try:

    file = open("example.txt", "r")

    content = file.read()

except FileNotFoundError:

    print("File not found!")

finally:

    print("Execution completed.")

Output (if the file doesn’t exist):

File not found!

Execution completed.

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5. Raising Exceptions in a try Block

try:

    age = int(input("Enter your age: "))

    if age < 0:

        raise ValueError("Age cannot be negative")

except ValueError as e:

    print(f"Error: {e}")

Input/Output:

Enter your age: -5

Error: Age cannot be negative