VER.0

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

class KgToG
{
    private:
 int kg, g;
    public:
 void getKg();
 void calcKgToG();
 void prnKgToG();
};

void KgToG::getKg()
{
    cout << "몇 kg? : ";
    cin >> kg;
}

void KgToG::calcKgToG()
{
    g = kg * 1000;
}

void KgToG::prnKgToG()
{
    cout << kg << "kg -> " << g << "g"<< endl;
}

int main()
{
    KgToG my;

    my.getKg();
    my.calcKgToG();
    my.prnKgToG();
}

VER.1

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

class KgToG
{
    private:
 int kg, g;
    public:
 void getKg();
 void calcKgToG();
 void prnKgToG();
 void clear();
};

void KgToG::getKg()
{
    cout << "몇 kg? : ";
    cin >> kg;
}

void KgToG::calcKgToG()
{
    g = kg * 1000;
}

void KgToG::prnKgToG()
{
    cout << kg << "kg -> " << g << "g"<< endl;
}
void KgToG::clear()
{
 kg = 5;
}

int main()
{
    KgToG my,your;

    my.getKg();
    my.calcKgToG();
    my.prnKgToG();

 your.clear();
 your.calcKgToG();
 your.prnKgToG();
}

VER.2

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

class KgToG
{
    private:
 int kg, g;
    public:
 void getKg();
 void calcKgToG();
 void prnKgToG();
 void clear();
};

void KgToG::getKg()
{
    cout << "몇 kg? : ";
    cin >> kg;
}

void KgToG::calcKgToG()
{
    g = kg * 1000;
}

void KgToG::prnKgToG()
{
    cout << kg << "kg -> " << g << "g"<< endl;
}
void KgToG::clear()
{
 kg = 5;
}

int main()
{
    KgToG my,your;
 int n;

 cout << "몇 kg?";
 cin >>n;
 KgToG k3(n);
 k3.getKg();
 k3.calcKgToG();
 k3.prnKgToG();

    my.getKg();
    my.calcKgToG();
    my.prnKgToG();
 

 your.clear();
 your.calcKgToG();
 your.prnKgToG();

}