You could modify the code from the HandlingExceptions – Python Wiki:
def collatz(number):
if number % 2 == 0:
print(number // 2)
return number // 2
elif number % 2 == 1:
print(3 * number + 1)
return 3 * number + 1
has_input_int_number = False
while has_input_int_number == False:
try: # try to convert user input into a int number
x = int(input("Enter a number: "))
has_input_int_number = True # will only reach this line if the user inputted a int
while x != 1:
x = collatz(x)
except ValueError: # if it gives a ValueError
print("Error: Please enter a numerical int value.")
Example Usage:
Enter a number: a
Error: Please enter a numerical int value.
Enter a number: 1.5
Error: Please enter a numerical int value.
Enter a number: 5
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solved how to use a while loop in my python code