public static string[] Tokenize(string text)
{
StringBuilder sb = new StringBuilder(text);
char[] invalid = "!-;':'\",.?\n\r\t".ToCharArray();
for (int i = 0; i < invalid.Length; i++)
sb.Replace(invalid[i], ' ');
return sb.ToString().Split(new[] { ' ' }, System.StringSplitOptions.RemoveEmptyEntries);
}