c++ 读取一行的2个数

#include <iostream>

using namespace std;

double harmonicMean(double x, double y);

int main() {

	double x, y;

	while (cin >> x >> y) { // 这一步是读取一行的两个数

		if (0 == x || 0 == y) break;

		cout << harmonicMean(x, y) << endl;

	}

	return 0;

}

double harmonicMean(double x, double y) {

	return 2.0 * x * y / (x + y);

}