Fungsi mencari luas, keliling dan diameter Linkaran

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    int r;
    float phi = 3.14;


    cout << " Masukkan jari-jarinya: ";
    cin >> r;
 
    cout << " Diameter Lingkaran : " << 2 * r << endl;
    cout << " Keliling Lingkaran : " << 2 * phi * r << endl;
    cout << " Luas Lingkaran : " << phi * r * r << endl;
    cout << " Volume bola : " << 1.3333333 * phi * r * r * r << endl;
 
 
    system("PAUSE");
    return EXIT_SUCCESS;
}