jQuery火箭图标返回顶部代码

一>

 1 #include "stdafx.h"
 2 #include<iostream>
 3 #include<string>
 4 #include<fstream>
 5 using namespace std;
 6 
 7 class Rectangle
 8 {
 9 private:
10     double length, width;
11 public:
12     Rectangle(double l, double w);
13 };
14 
15 
16 Rectangle::Rectangle(double l, double w) :length(l), width(w)
17 {}
18 
19 int main()
20 {
21     Rectangle rect(20.0, 10.3);
22     ofstream out("a.dat", ios_base::binary);     //文件的输出
23     if (out.is_open())                           //如果打开成功
24     {
25         out.write((char*)&rect, sizeof(Rectangle));//把Rectangle类的rect成员写入
26         out.close();                             //注意:此步一定不能省
27     }
28     char* buf = new char[sizeof(Rectangle)];     //缓冲区
29     ifstream in("a.dat", ios_base::binary);      //文件的写入
30     if (in.is_open())                            //如果文件打开成功
31     {
32         in.read(buf, sizeof(Rectangle));         //从in指定的已打开文件中读取Rectangle字节到buf中
33         in.close();                              //注意:此步一定不能省
34     } 
35     return 0;
36 }

结果(注意:.dat文件要用WinHex打开，网上有下载):

二>

 1 #include "stdafx.h"
 2 #include<iostream>
 3 #include<string>
 4 #include<fstream>
 5 using namespace std;
 6 
 7 class Rectangle
 8 {
 9 private:
10     double length, width;
11 public:
12     Rectangle(double l, double w);
13     void displayArea() { cout << length * width << endl; }
14 };
15 
16 
17 Rectangle::Rectangle(double l, double w) :length(l), width(w)
18 {}
19 
20 int main()
21 {
22     int a[] = { 6,8,2,1 };
23     Rectangle rect(20.0, 10.3);
24     ofstream out("a.dat", ios_base::binary);
25     if (out.is_open())
26     {
27         out.write((char*)&rect, sizeof(Rectangle));
28         out.write((char*)a, 4 * sizeof(int));  //对数组来说，数组有n个元素那么后面就是n*sizeof(int)
29         out.close();
30     }
31     char* buf = new char[sizeof(Rectangle)];
32     char* buf2 = new char[4 * sizeof(int)];
33     ifstream in("a.dat", ios_base::binary);
34     if (in.is_open())
35     {
36         in.read(buf, sizeof(Rectangle));
37         in.read(buf2, sizeof(int) * 4);
38         int *a = new int[4];
39         memcpy(a, buf2, 4 * sizeof(int));
40         cout << a[3] << endl;
41         delete[] a;
42         in.close();
43 
44         Rectangle* pr = (Rectangle*)buf;
45         pr->displayArea();
46     }
47     delete[] buf;
48     return 0;
49 }

结果:

三>

 1 #include "stdafx.h"
 2 #include<iostream>
 3 #include<string>
 4 #include<fstream>
 5 using namespace std;
 6 
 7 class Rectangle
 8 {
 9 private:
10     double length, width;
11 public:
12     Rectangle(double l, double w);
13     void displayArea() { cout << length * width << endl; }
14 };
15 
16 
17 Rectangle::Rectangle(double l, double w) :length(l), width(w)
18 {}
19 
20 int main()
21 {
22     fstream file("a.txt", ios_base::out | ios_base::app);
23     if (file.is_open())
24     {
25         file << "Hello world!";
26         file.close();
27 
28     }
29     file.open("a.txt", ios_base::in);
30     if (file.is_open())
31     {
32         while (file.good())
33         {
34             string words;
35             file >> words;
36             cout << words << " ";
37         }
38         file.close();
39         cout << endl;
40     }
41     return 0;
42 }

结果:(文件中与命令提示框输出得一样哦)