C++ allocates abnormally large amout memory for variables

Question

I recently got to know an integer takes 4 bytes from the memory.

First ran this code, and measured the memory usage:

int main()
{
   int *pointer;
         


        

Answer 1

Memory for individually allocated dynamic objects is not required to be contiguous. In fact, due to the alignment requirements for new char[N] (namely to be aligned at alignof(std::maxalign_t), which is usually 16), the standard memory allocator might just never bother to return anything but 16-byte aligned memory. So each int allocation actually consumes (at least) 16 bytes. (And further memory may be required by the allocator for internal bookkeeping.)

The moral is of course that you should be using std::vector(1000000) to get a sensible handle on one million dynamic integers.