Queue implementation via dynamic array.

queue.cpp

#include <iostream>

using namespace std;


class queue {
	int *arr;
	int f,r, max;
public:
	queue(int n) {
		max = n;
		arr = new int[max];
		f=-1;r=-1;
	}
	void enqueue(int n);
	void dequeue();
	void peek();
};


int main() {
	queue q(10);
	q.enqueue(2);
	q.enqueue(23);
	q.enqueue(42);
	q.dequeue();
	q.enqueue(12);
	q.peek();
	return 0;
}


void queue::enqueue(int n) {
	if(r==max-1 && f==0) {
		cout<<"Overflow"<<endl;
	}

	else {
		if(r==max) {
			for (int i=0;i<r-f;i++) {
				arr[i] = arr[f+i];
			}
			r-=f;
		}

		if(f==-1) {
			f=0;
		}
		r+=1;
		arr[r] = n; 
	}
}

void queue::dequeue() {
	if(f==-1) {
		cout<<"Underflow"<<endl;
	}

	else {
		f+=1;
		if(f>r) {
			f = -1;
			r = -1;
		}
	}
}

void queue::peek() {
	if(f==-1 && r==-1) {
		cout<<"list is empty"<<endl;
	}

	else {
		for (int i=f;i<=r;i++) {
			cout<<arr[i]<<" ";
		}
	}
}