#include <iostream>
#include <vector>
#include <algorithm>

int main()
{
   std::vector<double> v{1.0,2.0,3.0};
   double prod=1.0;
   std::for_each(v.begin(),v.end(), [&prod] (double x) { prod *= x;});
   std::cout <<"product = "<< prod << "\n";
}