Check a string if it only contains letters from the alphabet and not numbers or other stuff in C#?

Question

I have a question. I'm researched it on the web and of course with the search function here on stackoverflow. I also found a few similiar question but they where either in another programming language or not exactly I want to do. So here is my question in detail:

I'm creating a simple console Hangman game (im a beginner). I'm doing this just on my own because I think I learn the most if I do it on my own. Anyway I ask the user for his word and save it into a variable. I also make it Uppercase. Now I want to check if this word only contains valid letters from the alphabet. Than I want to put this in a if condition so he will be ask again if he enters for example a number.

But I have no idea how to do this? I tried it with the tryparse method and contains but I can't come to a solution. So I'm asking you kindly how to do this?

My code:

class Hangman
{
    private string enteredWord;
    private char guessedLetter;



    public void Start()
    {
        enteredWord = AskUserForWord();
        Console.WriteLine(enteredWord);
        Console.ReadLine();

    }

    private string AskUserForWord()
    {



        Console.WriteLine("Bitte gib ein Wort ein das es zu erraten gilt. Sag deinem Mitspieler er soll weg sehen: ");
        string word = ToUpper(Console.ReadLine());

        if ()
        return word;
    }


    private string ToUpper(string word)
    {

        return word.ToUpper();

    }

}

Answer 1

First reference system.linq:

using System.Linq;

then modify your AskUserForWord() function:

while (true)
{
    Console.WriteLine("Bitte gib ein Wort ein das es zu erraten gilt. Sag deinem Mitspieler er soll weg sehen: ");
   string word = Console.ReadLine().ToUpper();

   if (word.All(c => char.IsLetter(c))
       return word;

   Console.WriteLine("Also bitte, nur Buchstaben sind hier erlaubt!");
}

Answer 2

This should do the job :

bool result = input.All(Char.IsLetter);

and also a regex solution :

Regex.IsMatch(theString, @"^[\p{L}]+$");

The Char.IsLetter is the better solution since it counts as a letter any language alphabets. This regex will also count them but still it looks more compact with IsLetter

Answer 3

You can use regular expressions.

For alphabets,

Regex.IsMatch(word, @"^[a-zA-Z]+$");

Answer 4

可以对此进行检查。

bool isLettersOnly = !word.Any(c => !char.IsLetter(c));

Answer 5

read up on Regex aka Regular expressions, they are good for describing exactly how you want your input to be, in your case it would be something like:

Regex(@"^[a-zA-Z]*");

this means only accept strings which consist of alphabetic characters.

look at this example https://msdn.microsoft.com/en-us/library/3y21t6y4(v=vs.110).aspx to understand how to use it.

Answer 6

You may also try with a Regular expression.

Match match = Regex.Match("Testing a valid input ", @"(?i)^[a-z]+");

            if (match.Success)
            {
                //validation passed
            }