#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#define SIZE 64
#define NUM 10

struct person
{
    unsigned long ssn;
    char fn[SIZE];
    char ln[SIZE];
};

struct person* array[NUM];
int count = 0;

void free_people()
{
    int i;
    for( i = 0 ; i < NUM ; ++i)
    {
        free(array[i]);
        array[i] = NULL;
    }
}

void print_people()
{
    int i;
    printf("=======================================================\n");
    for( i = 0 ; i < NUM ; ++i)
    {
        printf("%lu %s, %s\t[%p] [%p]\n", array[i]->ssn, array[i]->ln, 
                array[i]->fn, &array[i], array[i]);
    }
    printf("=======================================================\n");
}

void add_person(unsigned long ssn, const char* fn, const char* ln)
{
    array[count] = (struct person*) malloc(sizeof(struct person));
    array[count]->ssn = ssn;
    strncpy(array[count]->fn, fn, SIZE-1);
    array[count]->fn[SIZE-1] = 0;
    strncpy(array[count]->ln, ln, SIZE-1);
    array[count]->ln[SIZE-1] = 0;
    count++;
}

int sort_people(const void* one, const void* two)
{
    struct person* p1 = *(struct person**)one;
    struct person* p2 = *(struct person**)two;
    return p1->ssn - p2->ssn;
}

int main(int argc, char** argv)
{
    add_person(123123123, "Alan     ", "Alda");
    add_person(666111666, "Betty    ", "Boop");
    add_person(411411411, "Cassius  ", "Clay");
    add_person(112123123, "Donnie  ", "Darko");
    add_person(555121255, "Eagle     ", "Eye");
    add_person(888444888, "Fred", "Flinstone");
    add_person(333111333, "Gale  ", "Glimmer");
    add_person(911911911, "Herbert", "Hoover");
    add_person(345123369, "Igor ", "Ilgaskus");
    add_person(111222333, "James ", "Jameson");

    print_people();

    qsort(array, NUM, sizeof(struct person*), sort_people);

    print_people();

    free_people();

    return 0;
}