Question

I need to create a pool of objects to eliminate dynamic allocations. Is it efficient to use std::stack to contain pointers of allocated objects?

I suspect every time I push the released object back to stack a new stack element will be dynamically allocated. Am I right? Should I use std::vector to make sure nothing new is allocated?

Answer 1

Whether a stack is suited for your particular purpose or not is an issue I will not deal with. Now, if you are concerned about the number of allocations, the default internal container for a std::stack is an std::deque<>. It will not need to allocate new memory for the stack in each push (as long as it has space) and when it allocates it does not need to relocate all existing elements as an std::vector<> would.

You can tell the stack to use an std::vector<> as underlying container with the second template argument:

std::stack< int, std::vector<int> > vector_stack;