字符串截取（包括html，BasicPage.cs类使用）

    /// <summary>
    /// 截断字符串(中文计一个字符宽度，其它计半个字符宽度)
    /// </summary>
    /// <param name="input">需截断的字符串</param>
    /// <param name="length">字符宽度</param>
    /// <returns>截断字符串(带"...")</returns>
    protected string truncatedChars(string input, int length)
    {
        input = Server.HtmlEncode(input);
        if (input.Length > length)
        {
            int pos = 0;
            string result = "";
 
            foreach (char chr in input)
            {
                if (Regex.IsMatch(chr.ToString(), "[^\x00-\xff]"))
                {
                    pos += 2;
                }
                else
                {
                    pos += 1;
                }
                result += chr.To