Truncate String

gistfile1.cs

        /// <summary>
        /// 根据字符长度截断字符串
        /// </summary>
        /// <param name="str">
        /// 需要截断的字符串
        /// </param>
        /// <param name="maxLength">
        /// 字符串允许的最大长度(包含的byte数)
        /// </param>
        /// <param name="isDetectChinese">
        /// 是否处理中文字符(把中文字符当作两个byte进行处理)
        /// </param>
        /// <param name="endstring">
        /// 截断后,新字符串的末尾显示,比如...
        /// </param>
        /// <returns>
        /// 截断后的字符串
        /// </returns>
        public static string Truncate(this string str, int maxLength, bool isDetectChinese=true, string endstring="...")
        {
            str = str.Default();
            if (!isDetectChinese)
                return str.Substring(0, Math.Min(maxLength, str.Length)) + endstring.Default();
            else
            {
                Regex reg = new Regex("[\u4e00-\u9fa5]");
                var _str = reg.Replace(str, "ch");//use "ch" replace the chinese char
                if (_str.Length > maxLength)
                {
                    int index = maxLength / 2;//the chinese char is 2 byte,but the index value is 1
                    for (int i = index, l = str.Length; i < l; i++)
                    {
                        var _length = reg.Replace(str.Substring(0, i), "ch").Length;
                        if (_length >= maxLength)
                        {
                            return str.Substring(0, i + maxLength - _length) + endstring.Default();
                        }
                    }
                }
                return str;
            }
        }