Question

I am trying to validate a string based on the inputed characters. I want to be able to set which characters are allowed besides characters and numbers. Below is my extension method:

public static bool isAlphaNumeric(this string inputString, string allowedChars)
{
    StringBuilder str = new StringBuilder(allowedChars);
    str.Replace(" ", "\\s");
    str.Replace("\n","\\\\");
    str.Replace("/n", "////");
    allowedChars = str.ToString();

    Regex rg = new Regex(@"^[a-zA-Z0-9" + allowedChars + "]*$");
    return rg.IsMatch(inputString);
}

The way I use this is:

s string = " te\m@as 1963' yili.ışçöÖÇÜ/nda olbnrdu" // just a test string with no meaning
if (s.isAlphaNumeric("ışŞö\Ö@üÜçÇ ğ'Ğ/.")) {...}

Of course it gives an error:

parsing "^[a-zA-Z0-9ışŞö\Ö@üÜçÇ\sğ'Ğ/.]*$" - Unrecognized escape sequence

the stringbuilder replace function is wrong which I am aware of. I want to be able to accept all characters given in the allowedChars parameter. This can also include slashes (any other characters similar to slashes I am not aware of?) Given this, how can I get my replace function work? and also is the way I am doing is correct? I am very very new to regular expressions and have no clue on how to work with them…

Answer 1

You need to use Regex.Escape on your string.

allowedChars = Regex.Escape(str.ToString());

ought to do it.