C++拷贝构造函数、移动构造函数

首先吐槽下，自己一开始搜索的时候，几乎网上所有的都是抄某一个人的，所以自己不得不自己做实验

（1）此时p不是将亡值，所以push_back调用拷贝构造函数

#include <vector>#include <iostream>using namespace std;class Person {public:Person(string name,int age):name(name),age(age){cout << "I have been created" << endl;}Person(const Person &p):name(p.name),age(p.age) {cout << "I have been copy created" << endl;}Person(Person &&p) :name(p.name),age(p.age) {cout << "I have been moved" << endl;}~Person() {cout<<"I have been destroyed"<<endl;}private:string name;int age;};int main(){cout << "emplace_back:" << endl;vector<Person> v1;v1.emplace_back("sunxu",24);vector<Person> v2;cout << "push_back:" << endl;Person p=Person("sunxu1",24);v2.push_back(p);//v1.push_back(Person("sunxu2",24));//v1.push_back(Person("sunxu2",24));//v1.push_back(Person("sunxu2",24));cout<<"destroy:"<<endl;return 0;}

（2）修改main代码如下：

int main() {cout << "emplace_back:" << endl;vector<Person> v1;v1.emplace_back("sunxu",24);vector<Person> v2;cout << "push_back:" << endl;//Person p=Person("sunxu1",24);//v2.push_back(p);v2.push_back(Person("sunxu2",24));//v1.push_back(Person("sunxu2",24));//v1.push_back(Person("sunxu2",24));cout<<"destroy:"<<endl;return 0;}

此时传入的是一个临时对象（将亡值），调用移动构造函数，同时调用析构函数释放临时对象。

（3）接下来考虑扩容问题，修改main如下：

int main() {cout << "emplace_back:" << endl;vector<Person> v1;v1.emplace_back("sunxu",24);vector<Person> v2;cout << "push_back:" << endl;//Person p=Person("sunxu1",24);//v2.push_back(p);cout<<"fisrt push back"<<endl;v1.push_back(Person("sunxu2",24));cout<<"second push back"<<endl;v1.push_back(Person("sunxu2",24));cout<<"third push back"<<endl;v1.push_back(Person("sunxu2",24));cout<<"destroy:"<<endl;return 0;}