c++ Initialising 2 different iterators in a for loop [duplicate]

Answer 1

It seems you need an inner_product algorithm.

#include 
#include 
#include 
#include 

struct my_plus 
{
    double operator()(int i, double d)
    {
        return d + i;
    }
};

struct my_multiplies 
{
    double operator()(int i, double d)
    {
        return d * i;
    }
};

int main()
{
    std::vector dubVec;
    std::vector intVec;
    double result = 0;

    dubVec.push_back(3.14);
    intVec.push_back(1);

    result = std::inner_product(intVec.begin(), 
                                intVec.end(), 
                                dubVec.begin(),
                                0.0,
                                my_plus(),
                                my_multiplies());
    std::cout << result << std::endl;
}

I used my own functors, because I suspect the standard multiplies and plus expect both operands to be of similar type, but I might be wrong.