类的构造、移动、赋值函数示例

#include <iostream>

using namespace std;

class Teacher {

   public:

    int id;

    int* studentIds{nullptr};

    int count;

   public:

    Teacher(int id, int count) {

        this->id = id;

        this->count = count;

        this->studentIds = new int[count];

    }

    Teacher(Teacher&& other) {

        this->id = other.id;

        this->count = other.count;

        this->studentIds = other.studentIds;

        other.studentIds = nullptr;

    }

    // copy构造函数尽量不给出实现，如果不给出，因为提供了移动copy，所以这个函数是不允许调用的

    // Teacher(Teacher& other) {

    //     this->id = id;

    //     this->count = count;

    //     this->studentIds = other.studentIds; //这里简单这么实现，通常需要深copy，否则可能出现内存被重复释放的问题

    // }

    Teacher& operator=(Teacher&& other) {

        if (this->studentIds) {

            delete this->studentIds;

        }

　　this->id = other.id;

       this->count = other.count;

       this->studentIds = other.studentIds;

    }

    // 这个函数尽量不提供，如果需要提供，则需要深copy，因为出现了移动赋值，如果不提供改函数，该函数是不允许使用的

    // Teacher& operator=(Teacher& other) {

    // }

    ~Teacher() {

        if (this->studentIds) {

            delete this->studentIds;

            this->studentIds = nullptr;

        }

    }

};

Teacher GetTeacher() {  // 借助了移动copy构造函数的能力，相当于返回了局部变量

    Teacher t(1, 4);

    for (int i = 0; i < t.count; i++) {

        t.studentIds[i] = i;

    }

    return t;

}

int main(int argc, char const* argv[]) {

    Teacher p = GetTeacher();

    cout << p.id << " " << p.count << endl;

    for (int i = 0; i < p.count; i++) {

        cout << p.studentIds[i] << " ";

    }

    cout << endl;

    return 0;

}