Question

is it safe to memcopy myvect.size()*sizeof(foo) bytes from the memoryadress of the first element of a

std::vector<std::pair<T1, T2> > myvect

into an array of

struct foo{
    T1 first;
    T2 second;
}

if the array is allocated with the same number of elements as the vector’s size?

thanks

Answer 1

No, a class containing T1 and T2 is not guaranteed the same layout or alignment as std::pair<T1, T2>, at least in C++98 (since std::pair is not a POD type). The story may be different in C++0x.