pointers.c

#include <stdio.h>

void addOne(int num);
void addOnePtr(int *num);

int main (int argc, const char * argv[]) {
    
	int i = 3; // an int
	printf("i == %d\n", i);
	printf("&i == %p\n", &i); // reference/address-of operator &
	
	int *ip = &i; // a pointer to an int, type (int *)
	printf("ip == %p\n", ip);
	printf("*ip == %d\n", *ip); // dereference operator *
	
	printf("--------\n"
		   "*ip = 4;\n");
	*ip = 4; // dereference operator *
	printf("ip == %p\n", ip);
	printf("&i == %p\n", &i);
	printf("*ip == %d\n", *ip);
	printf("i == %d\n", i);
	
	printf("--------\n");
	
	addOne(i);
	printf("i == %d\n", i);
	
	addOnePtr(&i);
	printf("i == %d\n", i);
	
    return 0;
}

void addOne(int num) {
	printf("addOne called -- num: %d (&num: %p)\n", num, &num);
	num++;
	printf("addOne: num == %d\n", num);
}

void addOnePtr(int *num) {
	printf("addOnePtr called -- num: %p (*num: %d)\n", num, *num);
	(*num)++;
	printf("addOnePtr: (num == %p) *num == %d\n", num, *num);
}

Practicing pointers?

Teaching them!

Ah, neat! This is a fun little demo… Should be enough to demystify them for anyone, I think.

Hopefully! I'm thinking of adding a section on arrays as well.