Question

George is creating a program that will ask the user to input their grade in school. George wants to prevent the program crashing if the user enters letters instead of a number. Which of the following can be used?

for loop


try block


ValueError signifier


trace table

Answer 1

To prevent the program from crashing if the user enters letters instead of a number, George can use a try block.

A try block is used in Python to catch and handle exceptions. By placing the user input code within a try block, George can attempt to convert the input to a number using int() or float() functions. If the user enters letters instead of a number, a ValueError will be raised. However, by including an except block that specifically handles the ValueError exception, George can gracefully handle the situation and provide appropriate error handling or feedback to the user.

Here's an example of how George can use a try block to handle the situation:

python

Copy code

try:

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

except ValueError:

print("Invalid input. Please enter a number for your grade.")

In this example, if the user enters letters instead of a number, a ValueError will be raised. The except block with ValueError specified will catch the exception and execute the code within it, printing an error message to the user.

The other options mentioned (for loop, ValueError signifier, trace table) are not directly applicable to handling this specific situation of preventing a program crash due to invalid user input.