#include <stdio.h>

//There are two factors at play for why our struct is taking up 12 bytes of memory
//1. C and C++ require that the members of a structure are allocated in declaration order
// This means that the address in memory for first must be less than second and second less than third

//2. Processors either require or prefer that types are alligned in memory such that they begin on an
//address boundry that is some multiple of it's size so if second was placed after first it would be 
//misaligned 

//So what we are seeing here is that the second member is padded so that it is ensured to falls on a 
//on a 4 byte boundry relative to the start of the structure

//typedef struct
//{
//	
//	short first; //xx__
//	int second; //xxxx
//	short third; //xx__ //this end is padded to ensure that if multiple structures were in an array that they would also be aligned
//} Layout;

//reordering can help align memory and reduce memory usage
// This results in an 8 byte struct
typedef struct
{	
	short first; //xx
	short third; //xx
	int second; //xxxx
} Layout;


int main()
{
	printf("short: (%d) bytes\n", (int) sizeof(short));

	printf("int: (%d) bytes\n", (int) sizeof(int));

	//What is interesting is that the struct as a whole occupies 12 bytes not 8 like we thought
	printf("struct: (%d) bytes\n", (int) sizeof(Layout));

	return 0;
}