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

void swap(int* a, int* b){
	int c = *a;
	*a = *b;
	*b = c;
}

void bubble_sort(int *tosort, int len){
	char finished = 0;
	while(!finished){
		finished = 1;
		for(int i = 0; i < len-1; i++)
			if(tosort[i] > tosort[i+1]){
				swap(tosort+i, tosort+i+1);
				finished = 0;
			}
	}
}

void print_array(int *toprint, int len){
	printf("{");
	for(int *item = toprint; item < toprint+len; ++item)
		if(toprint + len == item + 1)
			printf("%d", *item);
		else
			printf("%d,", *item);
	printf("}");
}

int main(){
	int a = 10;
	int *pa; // Stands for "pointer to a"
	pa = &a; // &a means "the memory address of a"
	
	printf("a = %d\n", a);
	*pa = 22; // *pa means "the thing pa points to" 
				// Alternative explanation:  "The thing at memory address pa"
	printf("a = %d\n", a);
	printf("a = %d (the thing that pa points to is %d)\n", *pa, *pa);
	printf("pa = %lx\n", pa); // lx:  64-bit unsigned in hex
	int b = 42;
	pa = &b;
	printf("b = %d (the thing that pa points to is %d)\n", *pa, *pa);
	printf("pa = %lx\n", pa); // lx:  64-bit unsigned in hex
	printf("&pa (memory address of pa) = %lx\n", &pa);

	// Pointers are the same as a size_t, but the compiler likes to know what they point to
	int array[] = {0, 10, 20, 30, 40, 50, 60, 70, 80, 90};
	array[5] = 100; // You can do this
	*(array+5) = 100; // Another way of saying it!
	/* // Causes bad behaviour, but NO warnings OR exceptions
	for(int i = 0; i < 100; i++){
		printf("Overwriting array[%d]\n", i);
		array[i] = 100;
	}
	*/
	// Standard way to print out everything in an array:
	for(int i = 0; i < 10; i++) // i++ happens at the end
		printf("Item %d is %d\n", i, array[i]);
		// i++ happens here
	
	// Alternative way using pointers
	for(int *item = array; item < array+10; item++)
		printf("%d\n", *item);

	// Silly short alternative:
	for(int *item = array; item < array+10; printf("%d\n", *(item++))) ;

	int *bob = array;
	bob[9] = 231;
	printf("array[9] = %d\n", array[9]);

	// Non-initialized array
	int fred[16];
	fred[15] = 22;
	// fred[0] through fred[14] are uninitialized (contain random values)
	printf("fred[14] = %d\n", fred[14]);

	int t;
	printf("t = %d\n", t);

	int ** ppa = &pa; // Pointer to the pointer we made earlier that points to b now
	**ppa = 7;

	printf("*pa = %d\n", *pa);
	*ppa = array+3;
	printf("*pa = %d\n", *pa);

	print_array(array, 10);
	printf("\n");
	print_array(fred, 16);
	printf("\n");

	bubble_sort(array, 10);
	print_array(array, 10);
	printf("\n");

	// An array on the heap! 32 integers.
	int *heap_array = (int*)malloc(32 * sizeof(int));
	for(int* item = heap_array; item < heap_array + 32; item++)
		*item = (size_t)item % 1024;
	print_array(heap_array, 32);
	free(heap_array);
	



	return 0;
}