用括号确定表达式的操作顺序

 1 #include <iostream>
 2 
 3 /* run this program using the console pauser or add your own getch, system("pause") or input loop */
 4 using namespace std;
 5 //定义YourClass类，
 6 class YourClass
 7 {
 8 //指定YourOtherClass是它的友元类
 9 friend class YourOtherClass;  
10 private:
11     int num;
12 public:
13     YourClass(int n){num=n;}
14     display(char *YCname){
15         cout<<YCname<<".num :";
16         cout<<num<<endl;
17     }
18 };
19 //定义YourOtherClass，它是YourClass类的友元类
20 class YourOtherClass
21 {
22 public:
23     //使用YourClass类的私有成员
24     void disp1(YourClass yc,char *YCname){ 
25          cout<<YCname<<".num :";
26         cout<<yc.num<<endl;   
27     }
28     //使用YourClass类的公共成员
29     void disp2(YourClass yc,char* YCname){
30         yc.display(YCname);       
31     }
32 };
33 //在main()函数中创建和使用YourClass和YourOtherClass类对象
34 
35 int main(int argc, char** argv) {
36         //声明YourClass类对象
37     YourClass a(10),b(100);
38 
39     //显示a和b对象的值
40     cout<<"YourClass:"<<endl;
41     a.display("a");
42     b.display("b");
43 
44     //声明YourOtherClass类对象
45     YourOtherClass temp;
46 
47     //通过temp显示a和b对象的值
48     cout<<"YourOtherClass:"<<endl;
49     temp.disp1(a,"a");
50     temp.disp2(b,"b");
51     return 0;
52 }