using qsort() to sort pointers to structs containing strings

Question

I\'m not sure if this is possible to do with qsort because what I want to sort (array of pointers to struct) is not what I am comparing (strings).

Here is an abridge

Answer 1

It should be something like this:

int
cmp(const void *p0, const void *p1)
{
        // pn is a pointer to an element of the array,
        // so, it's effectively a pointer to a pointer to a struct.
        // Therefore, we need to cast it appropriately to struct student **.
        // To get a pointer to a struct from it, we dereference it once,
        // hence the "*". Then we need to extract a pointer to the beginning
        // of a string, hence the "->".
        return strcmp((*(struct student **) p0)->lname,
                      (*(struct student **) p1)->lname);
}