区分全角和半角的字符串指定长度截取(或填充)

 
        /// <summary>
        /// 获取制定字符串的前L位字符，注：半角字符只算半个字符
        /// </summary>
        /// <param name="s">制定的字符串</param>
        /// <param name="l">长度</param>
        /// <param name="adddot">超出长度时追加的字符</param>
        /// <returns></returns>
        public static string SubGBString(string s, int l, string adddot)
        {
            string c = @"abcdefghijklmnopqrstuvwzxyABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@#$%^&*()-=_+[];',./{}:\<>? \|";
            string cc = "";
            int p = 0;
            for (int i = 0; i < s.Length; i++)
            {
                cc = s.Substring(i, 1);
                if (c.IndexOf(cc) >= 0)
                    p++;
                else
                    p = p + 2;

                if ((p - 1) / 2 >= l)
                {
                    string reval=s.Substring(0, i);
                    reval = reval + adddot;
                        return reval;
                }
            }

            return s;
        }

        /// <summary>
        /// 获取制定字符串的前L位字符，注：全角字符算2个字符
        /// </summary>
        /// <param name="s">制定的字符串</param>
        /// <param name="l">长度</param>
        /// <param name="r">长度不够时填充的字符</param>
        /// <returns></returns>
        public static string SubByteString(string s, int l, string r)
        {
            string c = @"abcdefghijklmnopqrstuvwzxyABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@#$%^&*()-=_+[];',./{}:\<>? \|";
            string cc = "";
            int p = 0;
            for (int i = 0; i < s.Length; i++)
            {
                cc = s.Substring(i, 1);
                if (c.IndexOf(cc) >= 0)
                    p++;
                else
                    p = p + 2;

                if (p + 1 > l)
                    return s.Substring(0, i) + "..";
            }
            if (r != "")
            {
                string str = r;
                for (int i = 0; i <= l; i++)
                {
                    str += r;
                }

                return s + "  " + str.Substring(0, l - p);
            }
            else
            {
                return s;
            }
        }

    /// <summary>
        /// 截取字符串（按全角长度，一个全角等于两个半角）
        /// </summary>
        /// <param name="str">字符串</param>
        /// <param name="length">截取长度（全角）</param>
        /// <returns></returns>
        public String InterceptString(String str, Int32 length)
        {
            if (str.Length > length)
            {
                string newStr = "";
                length = length * 2;
                foreach (char ch in str)
                {
                    if (ch >= 32 && ch <= 126)//半角
                    {
                        length--;
                    }
                    else// 全角
                    {
                        length = length - 2;
                    }

                    if (length < 0) break;
                    newStr += ch;
                }
                str = newStr;
            }
            return str;
        }

转载请注明出处：http://blog.csdn.net/dasihg/article/details/6781391