1 void test_write()
2 {
3 const int TEST_SIZE = 100000000;
4 const char* c_plus_write_file = "H://c_plus_write_file.txt";
5 const char* c_write_file = "g://c_write_file.txt";
6
7 cout << "Test size :" << TEST_SIZE << endl;
8 //c++ style writing file
9 ofstream of(c_plus_write_file);
10 //assert(of);
11 time_t start, end;
12 start = clock();
13 for (int i = 0; i < TEST_SIZE; ++i)
14 {
15 char tmp[1];
16 tmp[0] = char(i);
17 of.write(tmp, 1);
18 }
19 end = clock();
20 of.close();
21 cout << "C++ style: " << end - start << " ms" << endl;
22 //c style writing file
23 FILE* fp;
24 fopen_s(&fp, c_write_file, "w");
25 start = clock();
26 for (int i = 0; i < TEST_SIZE; ++i)
27 {
28 char tmp[1];
29 tmp[0] = char(i);
30 fwrite(tmp, 1, 1, fp);
31 }
32 end = clock();
33 fclose(fp);
34 cout << "C style: " << end - start << " ms" << endl;
35 cin.get();
36 }
37
38 //机器配置：
39 //vs2015,vs2017
40 //intel(R)Core(TM)i7-6700HQ CPU@2.6GHZ 2.59GHZ
41 //16.0GB内存 64位操作系统
42 //测试结果：BUF_SIZE越大，C++与C风格时间差越大，数据如下：
43 //BUF_SIZE= 1000: c++平均90ms c平均80ms
44 //BUF_SIZE= 100000000: c++平均70ms c平均30ms
45 //这是读取测试，对于写入操作二者相关则更显著：BUF_SIZE= 100000000: c++平均25秒 c平均20秒
46 void test_read()
47 {
48 const char* read_file = "g://c_write_file.txt";
49 const int BUF_SIZE = 100000000;
50 //char buf[BUF_SIZE];
51 char* buf = new char[BUF_SIZE];
52 time_t start, end;
53
54 //c style writing file
55 FILE* fp = fopen(read_file, "rb");
56 assert(fp);
57 start = clock();
58 int len = 0;
59 do
60 {
61 len = fread(buf, 1, BUF_SIZE, fp);
62 //cout<<len<<endl;
63 } while (len != 0);
64 end = clock();
65 fclose(fp);
66 cout << "C style: " << end - start << " ms" << endl;
67
68 //c++ style writing file
69 ifstream ifs(read_file, ios::binary);
70 assert(ifs);
71 start = clock();
72 while (!ifs.eof())
73 {
74 ifs.read(buf, BUF_SIZE);
75 }
76 end = clock();
77 ifs.close();
78 cout << "C++ style: " << end - start << " ms" << endl;
79
80 delete[] buf;
81 cin.get();
82 }
