#include <stdio.h> //standard input/output library
#include <stdlib.h> //malloc() 
#include <string.h>

struct Student
{
	char* name;
	int id;
	float gpa;
};

void print_student (struct Student std){
	printf("----------------------\n");
	printf("Name: %s\n", std.name);
	printf("ID: %d\n", std.id);
	printf("GPA: %f\n", std.gpa);
	printf("----------------------\n");
}

void sort_first_two(void** arr, int n, int (*cmp) (void* a, void* b)){
	if (n < 2) return;
	if (cmp(arr[0], arr[1]) == 0){
		//swap the two
		void* temp = arr[0];
		arr[0] = arr[1];
		arr[1] = temp;
	}
	return;
}

int compare_ints(void* a, void* b){
	int* ai = a, *bi = b;
	if (*ai < *bi)
		return 1;

	return 0;
}

int compare_stds(void* a, void* b){
	struct Student* ai = a, *bi = b;
	if (ai->id < bi->id)
		return 1;

	return 0;
}



int main()
{
	int size = 10;
	int** array = malloc(sizeof(int*) * size);
	for (int i = 0; i < size; ++i)
	{
		array[i] = malloc(sizeof(int));

		*(array[i]) = 100 - i; 
	}

	printf("Before sorting...\n");
	for (int i = 0; i < size; ++i)
	{
		printf("%d ", *(array[i]));
	}
	printf("\n");

	sort_first_two((void**)array, size, compare_ints);

	printf("After sorting...\n");
	for (int i = 0; i < size; ++i)
	{
		printf("%d ", *(array[i]));
	}
	printf("\n");


	struct Student** std_arr = malloc(sizeof(struct Student*) * 2);

	std_arr[0] = malloc(sizeof(struct Student));
	std_arr[0]->name = "Roger";
	std_arr[0]->id = 9999;
	std_arr[0]->gpa = 3.5;

	std_arr[1] = (struct Student*) malloc(sizeof(struct Student));
	std_arr[1]->name = "asdfjasdkl";
	std_arr[1]->id = 8888;
	std_arr[1]->gpa = 3.0;


	printf("Before sorting...\n");
	for (int i = 0; i < 2; ++i)
	{
		print_student(*(std_arr[i]));
	}
	printf("\n");

	sort_first_two((void**)std_arr, 2, compare_stds);

	printf("After sorting...\n");
	for (int i = 0; i < 2; ++i)
	{
		print_student(*(std_arr[i]));
	}
	printf("\n");


	for (int i = 0; i < 2; ++i)
	{
		free(std_arr[i]);
		std_arr[i] = NULL;
	}
	free(std_arr);
	std_arr = NULL;
	

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






	return 0;
}