Save pointer's memory address

Question

I have to implement a function that returns the memory address of a pointer when I allocate it with malloc(). I know that malloc(value) allocates an area on the heap which is of size value.

I know how to implement the code for printing the memory address of that pointer:

    void *s = malloc (size)
    printf("%p\n",s);

My question is, how can I save the value printed by that code in an int or string (e.g. char *)?

Answer 1

Storing the value of the pointer (i.e. the memory location of some variable) in a string can be done much like you've used printf:

char buf[128];
void *s = malloc (size);
sprintf(buf, "%p\n",s);

To 'save' the value into an integer (type) you can do a simple cast:

void *s = malloc (size);
size_t int_value = (size_t)s;

Since in c you never know what your machine address pointer length is, this (technically) isn't guaranteed to work quite right; both of these methods can go wrong with wacky architectures or compilers.