重载运算符 加号

方式1: 重载+运算符：全局函数作为友元 完成运算符重载+

1+1 这种情况下 不需要重载 编译器能够计算
#千锋教育#

案例两个对象相加

#include <iostream>
#include<string.h>
using namespace std;
class Person
{
    //设置成友元函数 在函数内 访问Person类中的所有数据
    friend ostream& operator<<(ostream &out, Person &ob);
    friend Person operator+(Person &ob1, Person &ob2);
private:
    char *name;
    int num;
public:
    Person()
    {
        this->name = NULL;
        this->num = 0;
        cout<<"无参构造"<<endl;
    }
    Person(char *name, int num)
    {
        this->name = new char[strlen(name)+1];
        strcpy(this->name,name);
        this->num = num;
        cout<<"有参构造"<<endl;
    }
    //普通的成员函数
    void printPerson(void)
    {
        cout<<"name = "<<name<<", num = "<<num<<endl;
    }
    ~Person()
    {
        if(this->name != NULL)
        {
            delete [] this->name;
            this->name = NULL;
        }
        cout<<"析构函数"<<endl;
    }
};

//全局函数作为友元 完成运算符重载<<
ostream& operator<<(ostream &out, Person &ob)//out=cout, ob =ob1
{
    //重新实现 输出格式
    out<<ob.name<<", "<<ob.num;

    //每次执行为 返回值得到cout
    return out;
}
//全局函数作为友元 完成运算符重载+
Person operator+(Person &ob1, Person &ob2)//ob1 ob2
{
    //name+name(字符串追加)
    char *tmp_name = new char[strlen(ob1.name)+strlen(ob2.name)+1];
    strcpy(tmp_name,ob1.name);
    strcat(tmp_name,ob2.name);

    //num+num（数值相加）
    int tmp_num = ob1.num+ob2.num;
    Person tmp(tmp_name, tmp_num);

    //释放tmp_name的空间
    if(tmp_name != NULL)
    {
        delete [] tmp_name;
        tmp_name = NULL;
    }

    return tmp;
}
void test01()
{
    Person ob1("lucy",18);
    //普通的成员函数 遍历信息
    //ob1.printPerson();

    //cout默认输出方式 无法识别 自定义对象 输出格式
    //cout<<ob1<<endl;//err

    //运算符重载的调用方式1:
    operator<<(cout, ob1)<<endl;
    //运算符重载的调用方式2:
    //对方法1 进行优化 去掉operator,第一个参数 放在运算符<<的左边  第二个参数 放在运算符<<的右边
    cout<<ob1<<endl;//等价operator<<(cout, ob1);

    Person ob2("bob",19);
    cout<<ob1<<" "<<ob2<<endl;
}

void test02()
{
    Person ob1("lucy",18);
    Person ob2("bob", 19);

    cout<<ob1<<endl;
    cout<<ob2<<endl;
    //Person ob3 = operator+(ob1,ob2);
    Person ob3 = ob1+ob2;
    cout<<ob3<<endl;
}
int main(int argc, char *argv[])
{
    test02();

    return 0;
}

运行结果：

方式2: 重载+运算符：成员函数 完成运算符重载+

#include <iostream>
#include<string.h>
using namespace std;
class Person
{
    //设置成友元函数 在函数内 访问Person类中的所有数据
    friend ostream& operator<<(ostream &out, Person &ob);
private:
    char *name;
    int num;
public:
    Person()
    {
        this->name = NULL;
        this->num = 0;
        cout<<"无参构造"<<endl;
    }
    Person(char *name, int num)
    {
        this->name = new char[strlen(name)+1];
        strcpy(this->name,name);
        this->num = num;
        cout<<"有参构造"<<endl;
    }
    //成员函数 完成运算符重载 ob1用this代替 ob2用参数ob代替
    Person operator+(Person &ob)
    {
        //this ==> &ob1

        //name+name(字符串追加)
        char *tmp_name = new char[strlen(this->name)+strlen(ob.name)+1];
        strcpy(tmp_name,this->name);
        strcat(tmp_name,ob.name);

        //num+num（数值相加）
        int tmp_num = this->num+ob.num;
        Person tmp(tmp_name, tmp_num);

        //释放tmp_name的空间
        if(tmp_name != NULL)
        {
            delete [] tmp_name;
            tmp_name = NULL;
        }

        return tmp;
    }

    //普通的成员函数
    void printPerson(void)
    {
        cout<<"name = "<<name<<", num = "<<num<<endl;
    }
    ~Person()
    {
        if(this->name != NULL)
        {
            delete [] this->name;
            this->name = NULL;
        }
        cout<<"析构函数"<<endl;
    }
};

//全局函数作为友元 完成运算符重载<<
ostream& operator<<(ostream &out, Person &ob)//out=cout, ob =ob1
{
    //重新实现 输出格式
    out<<ob.name<<", "<<ob.num;

    //每次执行为 返回值得到cout
    return out;
}

void test03()
{
    Person ob1("lucy",18);
    Person ob2("bob", 19);

    //Person ob3 = ob1.operator+(ob2);
    Person ob3 = ob1+ob2;
    cout<<ob3<<endl;
}
int main(int argc, char *argv[])
{
    test03();

    return 0;
}

运行结果：