// calculation: the diameter, circumference, and area 
// of a circle with a given radius 
#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;

main()
{
    const double pi=3.1415926;
    double radius, diameter, circumference, area;

    cout << "enter radius as float " << endl;
    cin >> radius;

    diameter = 2.0*radius;
    circumference = 2.0*pi*radius;
    area = pi*radius*radius;

    cout.setf(ios::fixed | ios::showpoint);
    cout.width(10);
    cout.precision(5);
    
    cout << "radius   = " << radius        << endl;
    cout << "diameter = " << diameter      << endl;
    cout << "circumf. = " << circumference << endl;
    cout << "area     = " << area          << endl;
    
    system("pause");
    return 0;
}