Checking if a string contains an int

Question

public static void nameAsk()
    {
        bool check = true;

        while (check)
        {
            Console.WriteLine("What is your name?");
            string name = Console.ReadLine();
            int userName;

            bool checkIfInt = int.TryParse(name, out userName);

            if (checkIfInt)
            {
                Console.WriteLine("Welcome " + name + "!");
                break;
            }
            else
            {
                Console.WriteLine("Please enter a name without numbers");
            }
        }
    }

I am attempting to check if the name contains an int, but no matter what I do, I can't seem to get the output I am looking for.

I have entered the following 3 outputs and these are the results I get:

[Input: "John2" | Output: "Please enter a name without numbers"]

[Input: "John" | Output: "Please enter a name without numbers"]

[Input: 9 | Output: "Welcome 9!"]

Fixed by changing bool checkIfInt = name.Any(Char.IsDigit), I then put it into my if statement, but set it to false, as follows:

bool checkIfInt = name.Any(Char.IsDigit);

if (!checkIfInt)
{
  Console.WriteLine("Welcome " + name + "!");
  break;
}
else
{
   Console.WriteLine("Please enter a name without numbers");
}
}

Should `John2` fail because it contains an `int`, or should it pass because it's not entirely an `int`? — Sergey Kalinichenko, Sep 16 '17 at 22:05
Possible duplicate of [Check if a string has at least one number in it using LINQ](https://stackoverflow.com/questions/1540620/check-if-a-string-has-at-least-one-number-in-it-using-linq) — Ousmane D., Sep 16 '17 at 22:07
or [In C#, how to check whether a string contains an integer?](https://stackoverflow.com/questions/18251875/in-c-how-to-check-whether-a-string-contains-an-integer) — Ousmane D., Sep 16 '17 at 22:08

score 7 · Accepted Answer · answered Sep 16 '17 at 22:02

7

int.ParseInt will pass only when name is an int, and has no other characters.

You can check if a string contains a number anywhere in it with LINQ using Any:

if (name.Any(Char.IsDigit)) {
    ...
}

answered Sep 16 '17 at 22:02

Sergey Kalinichenko

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1

I just set a bool var = name.Any(Char.IsDigit)), I had to make the var equal to false in order to obtain what I was looking for in my output, it now works, thank you!! – KlappDaddy Sep 16 '17 at 22:20

Checking if a string contains an int

1 Answers1