dnt截取字符串

        /**//// <summary>
        /// 字符串如果操过指定长度则将超出的部分用指定字符串代替
        /// </summary>
        /// <param name="p_SrcString">要检查的字符串</param>
        /// <param name="p_Length">指定长度</param>
        /// <param name="p_TailString">用于替换的字符串</param>
        /// <returns>截取后的字符串</returns>
        public static string GetSubString(string p_SrcString, int p_Length, string p_TailString) 
        { 
            string myResult = p_SrcString; 

            if (p_Length >= 0) 
            { 
                byte[] bsSrcString = Encoding.Default.GetBytes(p_SrcString); 

                if (bsSrcString.Length > p_Length) 
                { 
                    int nRealLength = p_Length; 
                    int[] anResultFlag = new int[p_Length]; 
                    byte[] bsResult = null; 

                    int nFlag = 0; 
                    for (int i = 0; i < p_Length; i++) 
                    { 

                        if (bsSrcString[i] > 127) 
                        { 
                            nFlag++; 
                            if (nFlag == 3) 
                            { 
                                nFlag = 1; 
                            } 
                        } 
                        else 
                        { 
                            nFlag = 0; 
                        } 

                        anResultFlag[i] = nFlag; 
                    } 

                    if ((bsSrcString[p_Length - 1] > 127) && (anResultFlag[p_Length - 1] == 1)) 
                    { 
                        nRealLength = p_Length + 1; 
                    } 

                    bsResult = new byte[nRealLength]; 

                    Array.Copy(bsSrcString, bsResult, nRealLength); 

                    myResult = Encoding.Default.GetString(bsResult); 

                    myResult = myResult + p_TailString; 
                } 

            } 

            return myResult; 
        }