Question

Why won’t this build in VS 2010 C++?

typedef float test[10];
std::vector<test> test_me(100); // wanted initial capacity of 100

While this builds fine

typedef float test[10];
std::vector<test> test_me_now;

Answer 1

Arrays are neither copy constructible, nor move constructible. std::vector requires at least one of those for most operations. Or at least, the operations that involve actually putting things into the vector. Since the default constructor doesn’t put anything into the vector, there’s no problems using it.

The unbecoming behavior of built-in arrays is why std::array was invented.