CODEWITHSUNDEEP
c#unicodewhile-loop
Miguel Cabrera
Miguel Cabrera

Reputation: 39

How to test if an input value = char A - Z in C#

 while (asteriskWord != hangCharacters && score < 5)
 {               
      while ( letter != ) //This is where I want to test for A-Z a-z
      { 
          Console.WriteLine("Enter a letter please");
          letter = Convert.ToChar(Console.ReadLine());
      }
 }

After the first while-loop I want to be able to place the input inside of a while loop that breaks if the value is = letters A-Z or a-z.

This is so that if the user enters the wrong information, the loop will continue to ask for the information.

Thank you for your time and consideration. Also I tried doing letter != 'A' && letter != 'a'...... and so on, but it didn't work for some reason.

Upvotes: 0

Views: 1416

Answers (3)

Vokinneberg
Vokinneberg

Reputation: 2017

Another option is to use a regular expression, like this:

        while (!Regex.IsMatch(letter, "[a-zA-Z]"))
        {
            Console.WriteLine("Enter a letter please!");
            letter = Console.ReadLine();
        }

Upvotes: 3

Jon Skeet
Jon Skeet

Reputation: 1501163

Well the simplest way would be to just use comparisons. If you definitely want to do it in a single expression, Glorfindel's answer is appropriate. However, all those brackets and the negation makes me nervous of the readability. I'd break it into a separate method:

while (!IsValidLetter(letter))
{
    ...
}

...

private static bool IsValidLetter(char letter)
{
    return (letter >= 'a' && letter <= 'z') ||
           (letter >= 'A' && letter <= 'Z');
}

Whichever you find more readable - the latter is easier to modify later, of course, if you end up with more complicated requirements.

Upvotes: 8

Glorfindel
Glorfindel

Reputation: 22651

Characters can be compared to each other, just like numbers:

while (!((letter >= 'A' && letter <= 'Z') || (letter >= 'a' && letter <= 'z'))) {
    Console.WriteLine("Enter a letter please");
    letter = Convert.ToChar(Console.ReadLine());
}

Upvotes: 13

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