Why free() doesn't really frees memory?

Question

i\'m doing some tests allocating and deallocating memory. This is the code i\'m using:

#include 
#include 

#define WAVE_SIZE          


        

Answer 1

When memory is allocated and later free'd, that memory still stays with the process but is marked as free so it can be allocated again. This is because otherwise the operating system have to alter the virtual memory mapping of the process each time you call malloc or free, which takes time.