1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5 using System.IO; 6 namespace namespace1   //命名空间 7 { 8     class Program 9     {10         static void Main(string[] args)11         {12             FileStream file = File.Open("F:/filename.txt"/*初始文件路径*/, FileMode.Open, FileAccess.Read);//打开初始文件13             FileStream file2 = File.Open("F:/filename2.txt"/*过滤后文件*/, FileMode.Create, FileAccess.Write);//创建处理后的文件14             file2.Close();//关闭file2文件流15             byte[] array = new byte[file.Length];//初始化字节数组16             file.Read(array, 0, array.Length);//读取流中的数据并把它写入字节数组中17             file.Close();   //关闭file1文件流  18             string str = Encoding.Default.GetString(array);  //将字节数组转化为字符串19             char[] ch = str.ToCharArray();  //将字符串转化为字符数组20             string str1 = "";           21             foreach (char c in ch)  //遍历ch 22             {23                 if ((c != ‘1‘) & (c != ‘2‘) & (c != ‘3‘) & (c != ‘4‘) & (c != ‘5‘) & (c != ‘6‘) & (c != ‘7‘) & (c != ‘8‘) & (c != ‘9‘) & (c != ‘0‘))24                 //判断字符不等于数字，可根据实际情况更改过滤条件   25                 {26                     str1 = str1 + c.ToString();//字符串拼接27                 }28             }29             string fullPath = "F:/filename2.txt";                                  //将字符串写入文件30             if (System.IO.File.Exists(fullPath)) 31             {32                 using (StreamWriter sw = new StreamWriter(fullPath, false, Encoding.Default)) 33                 {34                    sw.WriteLine(str1); 35                 } 36             }37         }38     }39 }