// examples of addresses and pointers
#include <stdlib.h>
int global_int;
int array[10];
int initialized = 5;
main(int argc, char *argv[]) {
	int local_int, i, *ip;

	// look at some initial variable values
	printf("global_int is at 0x%x and contains %d\n",
		&global_int, global_int);
	printf("local_int is at 0x%x and contains %d\n",
		&local_int, local_int);
	printf("initialized is at 0x%x and contains %d\n",
		&initialized, initialized);

	// pointers can point different places at different times
	ip = &global_int;
	*ip = 5;
	ip = &local_int;
	*ip = 23;
	ip = &initialized;
	*ip = 101;

	// we have indirectly changed the variables' values
	printf("global_int is at 0x%x and contains %d\n",
		&global_int, global_int);
	printf("local_int is at 0x%x and contains %d\n",
		&local_int, local_int);
	printf("initialized is at 0x%x and contains %d\n",
		&initialized, initialized);

	// an array name is simply a shorthand for the address of element 0
	printf("array is 0x%x and &array[0] is also 0x%x\n",
		array, &array[0]);
	// think about why array[1] is 4 bytes higher than array[0]
	printf("array[1] is at 0x%x\n", &array[1]);
	// it is important to understand pointer arithmetic !!!
	printf("array + 1 is also 0x%x\n", array + 1);

	// strings also have addresses and can act like character arrays
	printf("\"my string\" is at 0x%x\n", "my string");
	printf("\"my string\"[5] is %c\n", "my string"[5]);

	// you can even get the address of a function but do not need the &
	printf("main is at 0x%x\n", main);
	ip = (int *)main;
	printf("your first binary instruction code is 0x%x\n", *ip);

	// we access the argument list as an array of strings
	for(i = 0; i < argc; i++)
		printf("argv[%d] is 0x%x -> %s\n", i, argv[i], argv[i]);
	return(0);
}