Why is my pointer not null after free?

Question

void getFree(void *ptr)
{
    if(ptr != NULL)
    {
        free(ptr);
        ptr = NULL;
    }
    return;
}
int main()
{
char *a;
a=malloc(10);
getFree(a);
if(a==         


        

Answer 1

Pointers are stored as integers somewhere in memory.

When you do a = malloc(10);, a has some value, say 0x1.

When you call getFree(a);, the function copies a into void *ptr.

Now a=0x1 and ptr=0x1.

When you do ptr=NULL, only ptr is changed to NULL, but a is still 0x1..