C++11引用限定符

#include<iostream>#include<string>using namespace std;class Animal{public:Animal& operator=(const Animal& animal) &;//&引用限定符指定该赋值运算符只能用于左值 ;&&限定符指定赋值运算符只能用于右值 private:string name;int weight;}; Animal& Animal::operator=(const Animal& animal) &{if(this!=&animal){name=animal.name;weight=animal.weight;}cout<<"Animal::operator=(const Animal& animal)&"<<endl;return *this;}int main(){Animal bird1,bird2,bird3;move(bird1)=bird3;//error bird2=bird3;//ok}