Implementation of Realloc in C

Question

int getmin(int a, int b)
{
    return a

        

Answer 1

malloc does not initialize memory to zero. (calloc is the equivalent that does.) If you are seeing things set to zero, it's accidental.

I believe the library version of realloc uses length information in the heap that is not directly available. (And it may overestimate the original allocation, which means it might copy a little extra memory when using realloc to expand the allocation. This generally has no effect.)

realloc likely doesn't do a copy when shrinking an allocation.

Also, I should note that in same cases, you don't have to do a copy even when realloc increases the size, for example, if the next block in the heap is free.