Is there a way of applying a function to each member of a struct in c++?

Question

You have a simple struct, say:

typedef struct rect
{
    int x;
    int y;
    int width;
    int height;
}
rect;

And you want to multiply

Answer 1

No; there is no way to iterate over the members of a struct.

In this particular case, though, you can accomplish your goal by using an array:

struct rect
{
    // actually store the data in an array, not as distinct elements
    int values_[4];

    // use accessor/mutator functions to modify the values; it is often best to
    // provide const-qualified overloads as well.
    int& x()      { return values_[0]; }
    int& y()      { return values_[1]; }
    int& width()  { return values_[2]; }
    int& height() { return values_[3]; }

    void multiply_all_by_two()
    {
        for (int i = 0; i < sizeof(values_) / sizeof(values_[0]); ++i)
            values_[i] *= 2;
    }
};

(note that this example doesn't make much sense (why would you multiply x, y, height and width by two?) but it demonstrates a different way to solve this sort of problem)