c#StreamReader读取指定行的指定字符串

http://blog.csdn.net/Reyes11235813/article/details/5493331

问题：

在一个文件的自定行(LineNum)之后查找一个指定的字符串(queryString).

一下是我想到的两种办法和朋友的一种办法，希望看到这篇文章的大侠们也能提提建议。

现在的三中办法中算是第二种方法跑起来最高效了。一下是他们分别循环10，100，1000次的平均运行时间。

Processing 100%
counts: 10
avgCostTime1: 51ms
avgCostTime2: 25ms
avgCostTime3: 37ms
-------------------------
Processing 100%
counts: 100
avgCostTime1: 33ms
avgCostTime2: 17ms
avgCostTime3: 31ms
-------------------------
Processing 100%
counts: 1000
avgCostTime1: 39ms
avgCostTime2: 21ms
avgCostTime3: 37ms
-------------------------

 

Code:

  1 using System;  2 using System.Collections.Generic;  3 using System.Linq;  4 using System.Text;  5 using System.Reflection;  6 using System.IO;  7   8   9 namespace test 10 { 11     class Program 12     { 13         class StopWatch 14         { 15             private static int mintStart; 16  17             public static void Start() 18             { 19                 mintStart = Environment.TickCount; 20             } 21  22             public static long Elapsed() 23             { 24                 return Environment.TickCount - mintStart; 25             } 26         } 27  28  29         class MyFile 30         {         31             public static string search1(int lineNum, string queryString, string filePath) 32             { 33                 StringBuilder stringBillder = new StringBuilder(); 34                 FileStream fileStream = new FileStream(filePath, FileMode.Open); 35                 StreamReader streamReader = new StreamReader(fileStream); 36                 int currentLine = 1; 37                 while(-1 != (streamReader.Peek())) 38                 { 39                     if(currentLine < lineNum) 40                     { 41                         currentLine++; 42                         continue; 43                     } 44                     else 45                     { 46                         string tempLine = streamReader.ReadLine(); 47                         stringBillder.Append(tempLine); 48                         currentLine++; 49                     } 50                 } 51                 streamReader.Close(); 52                 fileStream.Close(); 53                 int tempIndex = stringBillder.ToString().IndexOf(queryString); 54                 if (tempIndex != -1) 55                 { 56                     return "Find! " + tempIndex; 57                 } 58                 else 59                 { 60                     return "Not Find!"; 61                 } 62             } 63  64             public static string search2(int lineNum, string queryString, string filePath) 65             { 66                 FileStream fileStream = new FileStream(filePath, FileMode.Open); 67                 StreamReader streamReader = new StreamReader(fileStream); 68                 int currentLine = 1; 69                 while (-1 != (streamReader.Peek())) 70                 { 71                     if (currentLine < lineNum) 72                     { 73                         currentLine++; 74                         continue; 75                     } 76                     else 77                     { 78                         int tempIndex = streamReader.ReadLine().IndexOf(queryString); 79                         if (tempIndex != -1) 80                         { 81                             streamReader.Close(); 82                             fileStream.Close(); 83                             return "Find! Line" + currentLine + "cols" + tempIndex; 84                         } 85                         currentLine++; 86                     } 87                 } 88                 streamReader.Close(); 89                 fileStream.Close(); 90                 return "Not Find!"; 91             } 92  93             public static string search3(int lineNum, string queryString, string filePath) 94             { 95                 FileStream fileStream = File.Open(filePath, FileMode.Open); 96                 StreamReader streamReader = new StreamReader(fileStream); 97                 string log = streamReader.ReadToEnd(); 98                 string[] arr = log.Split(new char[] { '/r', '/n' }); 99 100                 if (arr != null && arr.Length >= lineNum)101                 {102                     for (int i = lineNum; i <= arr.Length; i++)103                     {104                         int tempIndex = arr[i].IndexOf(queryString);105                         if (tempIndex != -1)106                         {107                             streamReader.Close();108                             fileStream.Close();109                             return "Found! Line:" + i + "Cols:" + tempIndex;110                         }111                     }112                 }113                 else114                 {115                     return "Error! Can not find the line.";116                 }117                 streamReader.Close();118                 fileStream.Close();119                 return "Not Find!";120             }121         }122         static void Main(string[] args)123         {124             string filePath = @"d:/WindowsUpdate.log";125             long costTime1 = 0L;126             long costTime2 = 0L;127             long costTime3 = 0L;128             string result = null;129             const int counts1 = 10;130 131 132             for (int i = 0; i < 3; i++)133             {134                 int tempCount = (int)Math.Pow(counts1, i + 1);135                 for (int j = 0; j < tempCount; j++)136                 {137                     StopWatch.Start();138                     result = MyFile.search1(800, @"Process: C:/Windows/system32/svchost.exe", filePath);139                     costTime1 += StopWatch.Elapsed();140                     //Console.Out.WriteLine(result);141                     //Console.Out.WriteLine(costTime + "ms");142 143                     StopWatch.Start();144                     result = MyFile.search2(800, @"Process: C:/Windows/system32/svchost.exe", filePath);145                     costTime2 += StopWatch.Elapsed();146                     //Console.Out.WriteLine(result);147                     //Console.Out.WriteLine(costTime + "ms");148 149                     StopWatch.Start();150                     result = MyFile.search3(800, @"Process: C:/Windows/system32/svchost.exe", filePath);151                     costTime3 += StopWatch.Elapsed();152                     //Console.Out.WriteLine(result);153                     //Console.Out.WriteLine(costTime + "ms");154                     Console.Write("Processing {0}%/r", (j+1)*100/tempCount);155                 }156                 Console.Out.WriteLine("/ncounts: " + tempCount);157                 Console.Out.WriteLine("avgCostTime1: " + costTime1 / tempCount + "ms");158                 Console.Out.WriteLine("avgCostTime2: " + costTime2 / tempCount + "ms");159                 Console.Out.WriteLine("avgCostTime3: " + costTime3 / tempCount + "ms");160                 Console.Out.WriteLine("-------------------------");161             }162             163             164 165             Console.ReadLine();166         }167     }168 }169