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

int compare_integers(const void* lhs, const void* rhs) {
    const int* lhs_int = lhs;  // No type cast needed to assign a
    const int* rhs_int = rhs;  // void* to a ▒▒▒* in C.
    fprintf(stderr, "// compare_integers(&%d, &%d)\n", *lhs_int, *rhs_int);

    if(*lhs_int < *rhs_int) {
        return -1;   // if the lhs number is less than the rhs number
    }
    else if(*lhs_int == *rhs_int) {
        return 0;    // equal
    }
    else {           // greater
        return 1;
    }
}

int main(int argc, char* argv[]) {
    /* void qsort(void *base, size_t nmemb, size_t size,          */
    /*                 int(*compar)(const void *, const void *)); */
    int array[] = {3, 5, 1};

    int num_elements = sizeof(array) / sizeof(array[0]); // == 3
    //                 12            / 4     // on our platform

    // Sort an *ARRAY* of integers.
    qsort(array,   num_elements, sizeof(array[0]), compare_integers);
    // Same as:
    //qsort(array, 3,            4,                compare_integers);

    for(int i = 0; i < num_elements; i++) {
        printf("%d\n", array[i]);
    }

    assert( *array == array[0] );
    return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */