C to C++ woe

Porting code from C to C++. Among other things changing this:

    struct foo x[count];
    for (unsigned i=0; i<count; i++) {
           x[count].XXX = YYY;
           ....
           function(&x);
    }

To this:

    std::vector<struct foo> x;
    for (unsigned i=0; i<count; i++) {
           x.emplace_back(YYY, ...);
           function(&x);
    }

Surprise, surprise, I got unexpected errors when accessing the function's
argument. Took me about 1h to figure out what's wrong. I think I'm gonna keep
this as a potential interview question :-)