C/C++中的拷贝构造函数和赋值构造函数
代码：
1 #include <iostream> 2 #include <cstdio> 3 4 using namespace std; 5 6 class A{ 7 public: 8 A(){ 9 cout<<"construct"<<endl; 10 } 11 ~A(){ 12 cout<<"destory"<<endl; 13 } 14 A(const A& a){ 15 cout<<"copy construct"<<endl; 16 } 17 A& operator=(const A& a){ 18 cout<<"assert construct"<<endl; 19 } 20 }; 21 22 //const A& func(const A& a){ //返回值也是引用，不调用拷贝构造函数 23 A func(const A& a){ //返回的时候需要调用拷贝构造函数 24 cout<<"in the func"<<endl; 25 return a; 26 } 27 28 int main(){ 29 30 A a1,a2; 31 cout<<"function called"<<endl; 32 a2 = func(a1); 33 cout<<"function finished"<<endl; 34 35 return 0; 36 }
输出：
construct construct function called in the func copy construct assert construct destory function finished destory destory
分析：
如果将代码23行注释掉并改为22行，输出变为
construct construct function called in the func assert construct function finished destory destory
