push_back_vs_emplace_back

#include <iostream>
#include <vector>
using namespace std;

class A {
public:
    A() {}
    A(string name) : m_name(name) { printName(__PRETTY_FUNCTION__); }
    ~A() { printName(__PRETTY_FUNCTION__); }
    // 拷贝构造函数
    A(const A &other) { m_name += "copy-" + other.m_name; printName(__PRETTY_FUNCTION__); }
    // 赋值运算符
    A& operator=(const A &other) {
        if (this != &other) {
            m_name += "assign-" + other.m_name;
            printName(__PRETTY_FUNCTION__);
        }
        return *this;
    }
    // 移动构造函数
    A(A &&other) { m_name += "move-" + other.m_name; printName(__PRETTY_FUNCTION__); }
    // 移动赋值运算符
    A& operator=(A &&other) {
        if (this != &other) {
            m_name += "moveassign-" + other.m_name;
            printName(__PRETTY_FUNCTION__);
        }
        return *this;
    }

    string m_name;
private:
    void printName(string funcName) { cout << funcName << "  \t" << m_name << endl; }
};

int main()
{
    vector<A> vec;
    vec.reserve(100);

    vec.push_back(string("a1"));
    printf("=============================\n");
    vec.emplace_back(string("a2"));
    printf("=============================\n");

    A *a3 = new A("a3");
    A *a4 = new A("a4");
    A *a5 = new A("a5");

    // 下面调用的拷贝构造函数
    vec.push_back(*a3);
    vec.emplace_back(*a3);

    // 下面2个当A有移动构造函数时，调用A的移动构造函数；否则调用拷贝构造函数
    vec.push_back(std::move(*a4));
    vec.emplace_back(std::move(*a5));

    printf("============ destruct ==============\n");

    return 0;
}