C++友元函数重载"++"和"--"运算符

 1 #include <iostream>
 2 #include <cstring>
 3 
 4 using namespace std;
 5 
 6 class one{
 7     public:
 8         one(int i);
 9         void print();
10         friend one operator++(one&);
11         friend one operator++(one&,int);
12 
13     private:
14         int i;
15 };
16 
17 one::one(int I){
18     i = I;
19 }
20 
21 void one::print(){
22     cout<<"i="<<i<<endl;
23 }
24 
25 one operator++(one &op){
26     ++op.i;
27     return op;
28 }
29 
30 one operator++(one &op,int){
31     one temp(op);
32     op.i++;
33     return temp;
34 }
35 
36 int main(){
37     one obj1(1),obj2(100);
38     obj1.print();
39     (++obj1).print();//隐式调用
40     (obj1++).print();
41     obj1.print();
42 
43     (operator++(obj2)).print();//显式调用
44     (operator++(obj2,1)).print();//此处的参数1可以取任意整数(int)
45     obj2.print();
46 
47     return 0;
48 }