Cpp："->"和"."的区别

environments：gcc version 8.1.0 (x86_64-posix-seh-rev0, Built by MinGW-W64 project)

class data{

public:

　　int x;

　　data(int vx):vx(x){}

　　void msg(){}

};

// create class data instances;

data d = data(3);

data* cpt = &d;

d.msg();

cpt->msg();

 

typedef  struct col{

　　collection(int id, float score):cid{id},cscore{score}{}

　　int cid;

　　float cscore;

} collection;

// create struct col object

collection c{1,145.3};

cout << c.cid << endl ;

cout << c.cscore <<endl;

collection* spt = &c;

cout << spt -> cid << endl;

cout << spt-> cscore << endl;

Cpp中“.”和“->”说明：

　　1、“.”是成员运算符，用于调取成员变量和成员函数；符号“.”的左边必须是实例对象（具体对象），举例为绿色字体；

　　2、“->”是地址运算符，用于引用成员变量和成员函数；符号“->”的左边是实例对象的地址或者类名（结构名），举例为黄色字体；

　　3、等价形式：d.msg() 和 (*cpt).msg() 等价；c.cid 和 (*spt).cid；

　　4、“.”和“->”常用于“类和结构”相关操作；

　　5、结构体初始化说明：传送门

下面是具体代码：

#include<iostream>

using namespace std;


class Info{

private:
    int iage;
    int iid;

public:
    Info(int age, int id):iage(age),iid(id){}
    void msg(){
        cout << "age = " << this->iage << "	";
        cout << "id = " << this->iid << endl;
    }

};


typedef    struct Data
{
    Data(int id, float math):did{id},dmath{math}{}
    float dmath;
    int did;
} data;



int main(){

    Info information = Info(30, 1);
    Info* cpt;
    information.msg();
    cpt = &information;
    cpt -> msg();


    data d{1,145};
    cout <<"d.id = " << d.did << "	";
    cout <<"d.math = " << d.dmath << endl;

    data* spt;
    spt = &d;
    cout <<"spt->id = " << spt->did << "	";
    cout <<"spt->math = " << spt->dmath << endl;

    return 0;
}

// result:
// age = 30        id = 1
// age = 30        id = 1
// d.id = 1        d.math = 145
// spt->id = 1     spt->math = 145