Regarding Dynamic Memory Allocation

[saurabh29789]

Is it safe to move(increment/decrement/re-position) the pointer to
whom the dynamic memory was allocated to??

I mean :

{

int *p, *q;

p = (int*)malloc(10*sizeof(int));

q=p;
p = p+5;
..
..
Some Code
..
..
p = q;

free(p);
}

In this code, will the memory be safely freed ?

Some one told me that if I move the pointer to point to some other
(valid) location and then even if I return it back to the previous
location (starting address of the dynamically allocated memory), then
it might lose some information that it stores after the dynamic
allocation is done and, thus, the memory blocks might not be freed.

Is it so?

 

[jameskuyper]

Is it safe to move(increment/decrement/re-position) the pointer to
whom the dynamic memory was allocated to??

Yes, but you have to either save (which is the simplest approach) or
recreate (which is much trickier) the original pointer value before
passing it to free().

I mean :

{

int *p, *q;

p = (int*)malloc(10*sizeof(int));

q=p;
p = p+5;
.
.
Some Code
.
.

You could, at this point, call free(p-5), though I would not recommend
it.

p = q;

free(p);

That works, though free(q) is equally good.

}

In this code, will the memory be safely freed ?
Yes.

Some one told me that if I move the pointer to point to some other
(valid) location and then even if I return it back to the previous
location (starting address of the dynamically allocated memory), then
it might lose some information that it stores after the dynamic
allocation is done and, thus, the memory blocks might not be freed.

Is it so?

No.