Question

I’m confused about the for each loop in C++. I have this code in a main game loop:

for each (Bubble b in bubbles){
    b.Update();
}
for each (Bubble b in bubbles){
    b.Draw();
}

It doesn’t update anything, but does draw 1 bubble.. What’s wrong with it?

EDIT: This code works

struct BubbleUpdater {
void operator()(Bubble & b) { b.Update(); }
} updater;
struct BubbleDrawer {
void operator()(Bubble & b) { b.Draw(); }
} drawer;

void OnTimer(){ //this is my main game loop
    std::for_each(bubbles.begin(),bubbles.end(),drawer);
    std::for_each(bubbles.begin(),bubbles.end(),updater);
}

Answer 1

Change your BubbleUpdater class to accept it’s argument by reference

struct BubbleUpdater {
void operator()(Bubble & b) { b.Update(); }
} updater;

With that, your call to std::for_each should work.

If your compiler supports it (and VC10 does), then you can use lambdas instead of creating a distant function object class. And yes, it’s standard c++, or will be soon enough.

std::for_each (bubbles.begin(), bubbles.end(), [](Bubble & b){
    b.Update();
});