C++语言基础(23)-拷贝构造函数

当以拷贝的方式初始化一个对象时，会调用一个特殊的构造函数，就是拷贝构造函数（Copy Constructor）。

例如：

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

class Student{
public:
    Student(string name = "", int age = 0, float score = 0.0f);  //普通构造函数
    Student(const Student &stu);  //拷贝构造函数（声明）
public:
    void display();
private:
    string m_name;
    int m_age;
    float m_score;
};

Student::Student(string name, int age, float score): m_name(name), m_age(age), m_score(score){ }

//拷贝构造函数（定义）
Student::Student(const Student &stu){
    this->m_name = stu.m_name;
    this->m_age = stu.m_age;
    this->m_score = stu.m_score;
   
    cout<<"Copy constructor was called."<<endl;
}

void Student::display(){
    cout<<m_name<<"的年龄是"<<m_age<<"，成绩是"<<m_score<<endl;
}

int main(){
    Student stu1("小明", 16, 90.5);
    Student stu2 = stu1;  //调用拷贝构造函数
    Student stu3(stu1);  //调用拷贝构造函数
    stu1.display();
    stu2.display();
    stu3.display();
   
    return 0;
}

其中将

Student stu2 = stu1;

Student stu3(stu1)

时，就调用了拷贝构造函数。