1     class Program 2     { 3         static void Main(string[] args) 4         { 5             while (true) 6             { 7                 Console.WriteLine("请输入字符串："); 8                 string s = getInput(0); 9                 Console.WriteLine("请输入截取的字节长度（整数）：");10                 int l = Convert.ToInt32(getInput(1));11                 s = GetSubStringByByte(s, l);12                 Console.WriteLine("输出的结果：" + s);13                 Console.WriteLine("................................................\n");14             }15         }16         static string getInput(int type)17         {18             while (true)19             {20                 string s = string.Empty;21                 try22                 {23                     s = Console.ReadLine();24                 }25                 catch { }26                 if (type == 0)27                 {28                     if (!string.IsNullOrWhiteSpace(s))29                     {30                         return s;31                     }32                     else33                     {34                         Console.WriteLine("请输入正确的字符串：");35                     }36                 }37                 else38                 {39                     int l = 0;40                     if (int.TryParse(s,out l))41                     {42                         return s;43                     }44                     else45                     {46                         Console.WriteLine("请输入正确的整数：");47                     }48                 }49             }50         }51         /// <summary>52         /// 按字节截取字符串53         /// </summary>54         /// <param name="s">所要截取的字符串</param>55         /// <param name="l">截取字节长度</param>56         /// <param name="endStr">后接字符串（如“...”）</param>57         /// <returns></returns>58         static public string GetSubStringByByte(string s, int l, string endStr = "")59         {60             string temp = s;61             if (string.IsNullOrEmpty(temp))62             {63                 return string.Empty;64             }65             else if (Regex.Replace(temp, "[\u4e00-\u9fa5]", "zz", RegexOptions.IgnoreCase).Length <= l)66             {67                 return temp;68             }69             int j = 0, k = 0;70 71             CharEnumerator ce = temp.GetEnumerator();72             while (ce.MoveNext())73             {74                 j += (ce.Current > 0 && ce.Current < 255) ? 1 : 2;75 76                 if (j <= l)77                 {78                     k++;79                 }80                 else81                 {82                     temp = s.Substring(0, k);83                     break;84                 }85             }86             return temp + endStr;87         }88     }