Data type validation in python - Strings

Question

I am currently writing some python code that asks for a users name. I need the program to validate whether the user's input is a string or not. If it is a string, The loop will break and the programme will continue. If the input is not a string (like a float, integer etc), It will loop around and ask the user to input a valid string. I understand that you can use the following code when you are checking for an integer;

while True:
try:
    number = int(input("Plese enter a number: "))
    break
except ValueError:
    print("Please enter a valid integer")

I was thinking that I could use something like this to check for a string;

while True:
try:
    word = str(input("Plese enter a string: "))
    break
except ValueError:
    print("Please enter a valid string")

But as far as I understand, the str() just converts the user's input to a string, regardless of the data that was entered.

Please help!

thanks

I don't quite get what you are trying to do. What's a valid string to you? — Ozgur Vatansever
– Ozgur Vatansever, Commented May 16, 2017 at 21:05
Possible duplicate of How to check if type of a variable is string? — Ozgur Vatansever
– Ozgur Vatansever, Commented May 16, 2017 at 21:07
So, I want the programme to check whether the user has typed in a string. If so, it will break the loop as shown in the code. If the user has entered another type of data (integer, float etc), It will tell them to try again. — Tech Dynasty
– Tech Dynasty, Commented May 16, 2017 at 21:07
It's always a string. Even if they type 487, you'll get a string. — user2357112
– user2357112, Commented May 16, 2017 at 21:09
Do you mean you want to know if the user entered only alphabetic characters (no numeric or special characters)? — MrMas
– MrMas, Commented May 16, 2017 at 21:14

Ozgur Vatansever · Accepted Answer · 2017-05-16 21:23:40Z

1

Based on the comments, it looks like you want to check if the input consists of alphabetic characters only. You can use .isalpha() method:

while True:
    word = input("Please enter a string: ")
    if word.isalpha():
        # Do something with valid input.
        break
    else:
        print("Please enter a valid string")

edited May 16, 2017 at 21:23

answered May 16, 2017 at 21:21

Ozgur Vatansever

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