Write a Python program using a while loop to calculate and display the factorial of a user-inputnumber. Ensure your program handles invalid inputs gracefully.

Sure, here is a simple Python program that calculates the factorial of a user-input number using a while loop. It also handles invalid inputs gracefully:

def calculate_factorial():
    while True:
        num = input("Enter a positive integer: ")
        if num.isdigit():
            num = int(num)
            if num >= 0:
                break
            else:
                print("Invalid input. Please enter a positive integer.")
        else:
            print("Invalid input. Please enter a positive integer.")

    factorial = 1
    while num > 1:
        factorial *= num
        num -= 1

    print("The factorial is: ", factorial)

calculate_factorial()

In this program:

1. We first define a function calculate_factorial().
2. Inside this function, we start a while True loop to keep asking for user input until a valid positive integer is entered.
3. We use the isdigit() method to check if the input is a number. If it is not, we print an error message and continue to the next iteration of the loop.
4. If the input is a number, we convert it to an integer and check if it is positive. If it is not, we print an error message and continue to the next iteration of the loop.
5. Once we have a valid positive integer, we calculate its factorial using a while loop.
6. Finally, we print the factorial.
7. We call the function calculate_factorial() to run the program.