Question

If the area pointed to was moved, a
free(ptr) is done.

Can you please explain the above line about realloc()? This line is from a man page for calloc, malloc, realloc and free.

Answer 1

I think this explains it better:

If sufficient space does not exist to
expand the current block in its
current location, a new block of the
size for size is allocated, and
existing data is copied from the old
block to the beginning of the new
block. The old block is freed, and the
function returns a pointer to the new
block.

Reference taken from realloc in C