malloc and realloc

Hi all,

I m relatively new to C. I have few queries related to malloc():

#1. When we perform malloc(), the memory allocated dynamically comes
from the heap area of the process in concern. Well, we then say that
the heap has shrinked. my query is: Is it that the heap physically
does not shrink but the perticular nodes are marked 'ALLOCATED' and
for subsequent calls to malloc() the memory manager remembers them and
does not reference them?

#2. With realloc(), if some pointer 'ptr' is pointing initially to a
perticular position in a buffer (char *buffer) then on performing a
realloc() on this buffer, what will be 'ptr' pointing to?

#3. whats the maximum memory size that we can allocate dynamically by
calling malloc() ?

thanx in advance

Ravs

.

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