A method that trims both white-space and control characters from a string, and its rather fast!

TrimFullString.cs

public static string TrimFullString(string str)
{
    int start = 0;
    int end = str.Length - 1;

    for (; start <= end; start++)
    {
        if (!Char.IsWhiteSpace(str[start]) &&
            !Char.IsControl(str[start]))
            break;
    }

    for (; end >= start; end--)
    {
        if (!Char.IsWhiteSpace(str[end]) &&
            !Char.IsControl(str[end]))
            break;
    }

    if (start > end)
        return String.Empty;
    else
        return str.Substring(start, end - start + 1);
}