Check if a string contains one of 10 characters

Question

I\'m using C# and I want to check if a string contains one of ten characters, *, &, # etc etc.

What is the best way?

Answer 1

If you just want to see if it contains any character, I'd recommend using string.IndexOfAny, as suggested elsewhere.

If you want to verify that a string contains exactly one of the ten characters, and only one, then it gets a bit more complicated. I believe the fastest way would be to check against an Intersection, then check for duplicates.

private static char[] characters = new char [] { '*','&',... };

public static bool ContainsOneCharacter(string text)
{
    var intersection = text.Intersect(characters).ToList();
    if( intersection.Count != 1)
        return false; // Make sure there is only one character in the text

    // Get a count of all of the one found character
    if (1 == text.Count(t => t == intersection[0]) )
        return true;

    return false;
}