The catch_error_str function isn't catching errors when the input is a integer. - Python

Question

Please don't be too harsh because I'm new to coding. The problem I'm having is that the function catch_error_str does not work. For example, when I enter "2" as an input then it says last_name is 2 instead of catching the error.

def catch_error_str():
    unvalid = True
    while unvalid:
        try:
            string = str(input())
            unvalid = False
            return string
        except ValueError:
            print("You must not enter any numbers")

def surname ():
    print("What is the surname of the lead booker ")
    last_name = catch_error_str()
    print(last_name)

print("Welcome to Copington Adventure Theme Park's automated ticket system\nplease press any button to see the ticket prices.")
enter = input()
print("\nAdult tickets are £20 each \nChild tickets are £12 each \nSenior citizen tickets are £11 each")
surname()

Leo Arad · Accepted Answer · 2021-01-17 13:06:37Z

2

Python don't have a problem to covert a number to a string and because of that, there is no error rasing.
You can try

def catch_error_str():
    unvalid = True
    while unvalid:
        try:            
            string = str(input())
            if not string.isalpha():
               raise ValueError
            unvalid = False
            return string
        except ValueError:
            print("You must not enter any numbers")

The isalpha() method of string will check if the input not containing numbers and if so it will raise the value error.

answered Jan 17, 2021 at 13:06

Leo Arad

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Comments

Celius Stingher · Accepted Answer · 2021-01-17 13:06:27Z

The value that is returned from Input() is of type str therefore, the conversion won't generate an error that you can catch with ValueError. Instead you should try to check the type() of the variable. Also, you are requiring the input within the try. I would use something like this:

def catch_error_str():
    unvalid = True
    while unvalid:
        string = input()
        try:
            string = float(string)
            print("You must not enter any numbers")
        except ValueError:
            unvalid = False
            return string

Since floats/ints can be converted to strings without any problem, I'm facing the problem the other way around. I am trying to convert it into a float, if I'm able to, it's because the value is numeric, hence the error. If I am not able to, then that means it will generate ValueError because it is text

niles87 · Accepted Answer · 2021-01-17 13:16:12Z

0

Input returns a string even if the user input is a digit.

name = input(“Enter last name: “)
if name.isdigit():
    unvalid = True

answered Jan 17, 2021 at 13:16

niles87

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Comments

Minu · Accepted Answer · 2021-01-17 13:27:37Z

0

If the prompt argument is present, it is written to standard output without a trailing newline. The function then reads a line from input, converts it to a string (stripping a trailing newline), and returns that. When EOF is read, EOFError is raised.

https://docs.python.org/3/library/functions.html#input

answered Jan 17, 2021 at 13:27

Minu

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