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

// *
// Meaning 1:  int *x; // x is the address of an integer, not an int itself
// 						// Note:  x is 8 bytes, not 4
// Meaning 2:  *x = 5;  // The int x points to should be 5
// Meaning 3:  x * 5;  // * means multiplication here!
// So how about this?
// int x = *y * *z;
//
// &
// Meaning 1:  The address of, &x is the address of x
// Meaning 2:  x && y // Logical and
// Meaning 3:  x & y // Bitwise and
// So how about this?
// if(&x & &y)
//
// x[0] is the same as *x
// x[1] is the same as *(x+1)

// One important pitfall:
int* x, y; // x is a pointer, y is NOT.  y is an int.
// I prefer this:
int *z;
// You can do this:
int *a, *b; // Both are pointers

void foo(int *A){
	*A = 100;
}

int* print_array(int *A, size_t len){
	printf("[");
	for(size_t i = 0; i < len; i++)
		printf("%d, ", A[i]);
	printf("\b\b]\n");
	return A;
}

int* range(size_t end){
	int *newarray = malloc(sizeof(int) * end);
	if(!newarray) // Error handling:  malloc may return 0!
		return 0;
	for(int i = 0; i < end; i++)
		newarray[i] = i;
	return newarray;
}

int main(){
	int x = 5;
	printf("%d\n", x);
	foo(&x);
	printf("%d\n", x);

	int numbers[10] = {0,1,2,3,4,5,6,7,8,9};
	print_array(numbers, 10);

	// An array on the heap!
	int *other_numbers = malloc(10 * sizeof(int));
	for(int i = 0; i < 10; i++)
		other_numbers[i] = i+100;
	print_array(other_numbers, 10);
	
	free(print_array(range(20), 20));

	free(other_numbers);
	return 0;
}