check alphanumeric characters in string in c#

Question

I have used the following code but it is returning false though it should return true

string check,zipcode;
zipcode=\"10001 New York, NY\";
check=isalpha         


        

Answer 1

    public static bool IsAlphaNumeric(string strToCheck)
    {
        return strToCheck.All(char.IsLetterOrDigit);
    }