excercise4.cpp: In member function `void q_type::q(int)':
excercise4.cpp:31: error: invalid types `int[int]' for array subscript
excercise4.cpp: In member function `int q_type::deq()':
excercise4.cpp:42: error: invalid types `int[int]' for array subscript

/* Goal: create a class 'queue' that maintains a circular queue of integers. make the queue size 
100 integers long, and demonstrate its use in a main function */

#include <iostream>
using namespace std;

#define SIZE 100

class q_type {
	int queue; //hold the queue
	int head, tail; //indexes of the head & tail of the queue
public:
	void init(); //init the queue
	void q(int num); //store the queue
	int deq(); //retrieve
};

//init the queue
void q_type::init() {
	head = tail = 0;
}

//place a value on the queue
void q_type::q(int num) {
	if(tail + 1 == head || (tail + 1 == SIZE && !head)) {
		cout << "Queue is full.";
		return;
	}
	tail++;
	if(tail == SIZE) tail = 0; //cycle
	queue[tail] = num;
}

//remove a value from the queue
int q_type::deq() {
	if(head == tail) {
		cout << "Queue is empty.";
		return 0;
	}
	head++;
	if (head == SIZE) head = 0; //cycle
	return queue[head];
}

int main() {
	q_type q1, q2; //initialize 2 queues
	int i;
		
	q1.init();
	q2.init();

	for(i = 0; i <= 10; i++) {
		q1.q(i);
		q2.q(i * i);
	}
	
	for(i = 0; i <= 10; i++) {
		cout << "Dequeue 1: " << q1.deq() << "\n";
		cout << "Dequeue 2: " << q2.deq() << "\n";
	}

	return 0;
}

    int queue;

    ...

    return queue[head];