文件指定行后查找字符串
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 else
114 {
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
