字符串按指定长度剪切 代码段

/// <summary>        /// 将指定字符串按长度进行剪切        /// </summary>        /// <param name="oldStr">需要截断的字符串</param>        /// <param name="maxLength">字符串的最大长度</param>        /// <param name="endWith">超过长度的后缀</param>        /// <returns>如果超过长度，返回截断后的新字符串加上后缀，否则，返回原字符串</returns>        public static string StringTruncat(string oldStr, int maxLength, string endWith)        {            if (String.IsNullOrEmpty(oldStr))                //throw new NullReferenceException("原字符串不能为空")；                return oldStr + endWith;            if (maxLength <1)                throw new Exception ("返回的字符串长度必须大于[0]")if(oldStr .Length >maxLength )    {        string strTmp=oldStr .Substring (0,maxLength );        if (string.IsNullOrEmpty (endWith )) return strTmp ;            else             return strTmp +endWith ;}return oldStr ; }