This

#include<iostream>
#include<string.h>
#include<cstdlib>
using namespace std;
/*
this pointer: 메소드의 첫번째 매개변수로 선언되어있다.

*/
class Obj{
 
    int a;
 
 
public: 
    Obj(int a=0){this->a=a;}
 
    void setA(int a){  // void setA(Obj * this, int a)
        this->a=a;
    }
    int getA(){
        return a;
    }
};
void main(){ 
 
    Obj obj;
    Obj obj2(100);
 
    // obj.setA(100);  // obj.setA(&obj, 100);
 
    cout << obj. getA() << endl;
    cout << obj2. getA() << endl;
 
 
 
 
}