Byte Queue

#include <iostream>

using namespace std;

const int array_length = 2048;

struct Q{
	int first;
	int last;
	unsigned char data[array_length];

	Q() : data{}, first(0), last(0){}
};

Q * create_queue();
void destroy_queue(Q * q);
void enqueue_byte(Q * q, unsigned char b);
unsigned char dequeue_byte(Q * q);
void defragment_array(Q * q);
void on_illegal_operation();
void on_out_of_memory();

Q * create_queue(){
	Q * newQ = new Q;

	if (!newQ){
		on_out_of_memory();
	}

	return newQ;
}

void destroy_queue(Q * q){
	delete[] q;
	q = 0;
}

void enqueue_byte(Q * q, unsigned char b){
	if (q->last == array_length && q->first == 0){
		cout << "Queue is full";
	}else if (q->last == array_length && q->first){
		defragment_array(q);
	}else{
		q->data[q->last] = b;
		q->last++;
	}
}

unsigned char dequeue_byte(Q * q){
	if (q->last){
		q->first++;
		return q->data[q->first - 1];
	}else{
		on_illegal_operation();
		return 0;
	}
}

void defragment_array(Q * q){
	int front_index = 0;

	for (int i = q->first; i <= q->last; i++, front_index++){
		q->data[front_index] = q->data[i];
	}

	q->last -= q->first;
	q->first = 0;
}

void on_illegal_operation(){
	cerr << "Illegal Opperation" << endl;
}

void on_out_of_memory(){
	cerr << "Out of memory" << endl;
}