1 #include<iostream>
 2 #include <cstringt.h>
 3 #include<vector>
 4 #include<windows.h>
 5 #include <ctime>
 6 using namespace std;
 7
 8
 9
10
11 int main()
12 {
13     clock_t start, finish;
14     //------------------------------------------------------内存映射方法;
15     start = clock();
16     //创建或打开文件内核对象;
17     HANDLE fileH = CreateFile("ldFeature.txt",
18         GENERIC_READ|GENERIC_WRITE,
19         FILE_SHARE_READ,
20         NULL,
21         OPEN_EXISTING,
22         FILE_ATTRIBUTE_NORMAL,
23         NULL);
24     if(fileH == INVALID_HANDLE_VALUE)
25     {
26         cout<<"error in CreateFile"<<endl;
27         return -1;
28     }
29
30     //创建一个文件映射内核对象;
31     HANDLE mapFileH = CreateFileMapping( fileH,
32         NULL,
33         PAGE_READWRITE,
34         0,
35         0,
36         "Resource " );
37     if(mapFileH == NULL)
38     {
39         cout<<"error in CreateFileMapping"<<endl;
40         return -1;
41     }
42
43     //将文件数据映射到进程的地址空间;
44     char * mapH = (char *)MapViewOfFile( mapFileH,
45         FILE_MAP_ALL_ACCESS,
46         0,
47         0,
48         0);
49     if(mapH == NULL)
50     {
51         cout<<"error in MapViewOfFile"<<endl;
52         return -1;
53     }
54
55     //读取数据;
56     char *buf = mapH;
57     double k;
58     int times = 300000*34;
59     for(int i = 1; i <= times; i++)
60     {
61         k = atof(buf);
62         buf = strstr(buf+9," ");
63         //cout<<k<<endl;
64     }
65     //关闭句柄;
66     UnmapViewOfFile(mapH);
67     CloseHandle(mapFileH);
68     CloseHandle(fileH);
69
70     finish = clock();
71     //打印耗时;
72     cout<<"time:"<<(double)(finish - start)/ CLOCKS_PER_SEC<<endl;
73
74     //------------------------------------------------------传统方法;
75     start = clock();
76
77     FILE *fp = fopen("ldFeature.txt","r");
78     if(fp == NULL)
79     {
80         cout<<"error in fopen"<<endl;
81         return -1;
82     }
83     for(int i = 1 ;i <= times; i++)
84     {
85         fscanf(fp,"%lf",&k);
86     }
87     fclose(fp);
88
89     finish = clock();
90     cout<<"time:"<<(double)(finish - start)/ CLOCKS_PER_SEC<<endl;
91
92
93     return 0;
94 }