Swapping objects using pointers

Question

I\'m trying to swap objects for a homework problem that uses void pointers to swap objects. The declaration of my function has to be:

void swap(void *a, voi         


        

Answer 1

You're close.

The problem is: you are "swapping" only pointers a and b which are local variables in the function.

I assume outside of the function you have some variables, let's call them:

void *x = ...;
void *y = ...;

When you call:

swap(x, y, some_size);

a and b points to the same objects as x and y respectively. Now, when you swap what a and b points too, x and y are still pointing to what they where pointing before.

To change what memory x and y points you would have to pass a pointer to the x variable, so a pointer to a pointer :)

Because you can't change function declaration you can only swap the content of the memory where x (and a) and y (and b) points to. Some solutions are in other answers :) Generally memcpy is what you want.