C++控制台实例——计算圆的直径，周长，面积

//计算圆的直径，周长，面积
#include <iostream>
using namespace std;
int main()
{
	float r;
	float pi = 3.14159;
	cout << "请输入圆的半径（R）：";
	cin >> r;
	float zj = 2 * r;
	float zc = 2 * pi * r;
	float mj = pi * r * r;
	cout << "圆的直径为：";
	printf("%.4f ", zj);
	cout << endl;
	cout << "圆的周长为：";
	printf("%.4f", zc);
	cout << endl;
	cout << "圆的面积为：";
	printf("%.4f", mj);
	cout << endl;
}