Question

You can allocate a std::vector which allocates aligned heap memory by defining your own allocator.
You can allocate a c-style array on the stack using declspec align.
But can you declare a tr1::array which guarantees that the element at index zero will be aligned?

Answer 1

tr1::array (and std::array and boost::array) are POD, so the memory occupied by the contents is coincident with the memory of the array. So, allocate the array however you need to, and construct it with placement new.

typedef std::tr1::array< MyClass, ary_sz > AryT;
void *array_storage = aligned_allocation( sizeof( AryT ) );
AryT *ary = new( array_storage ) AryT( initial_value );