类的默认构造函数，直接初始化，拷贝构造函数，赋值运算符的执行次数判断

#include<iostream>
#include<algorithm>
using namespace std;
class animal
{
public:
int a;
animal()
{
a = 0;
cout << "默认"<<endl;
}
animal(int x)
{
a = x;
cout << "直接初始化" << endl;
}
animal(const animal& x)
{
a = x.a;
cout << "拷贝" << endl;
}
animal& operator=(const animal& x)
{
cout << "=" << endl;
return *this;
}


animal& tesA(const animal& x)
{
return *this;
}
animal test2(const animal& x)
{
return *this;
}
};
int main()
{
animal A;
animal a2;
cout <<"事例1：";
a2 = A.tesA(A);
cout << "事例2：";
animal a3 = A.tesA(A);
cout << "事例3：" ;
a2 = A.test2(A);
cout << "事例4：" ;
animal a4 = a2.tesA(a2);

system("pause");
return 0;
}