queue.cpp

#include<iostream>
#define n 20
using namespace std;

class queue{
   
        int* arr;
        int front;
        int back;

    public:
      queue(){
        arr=new int[n];
        front=-1;
        back=-1;
     }

     void push(int x){
         if(back==n-1){
             cout<<"Queue overflow"<<endl;
         }
         back++;
         arr[back]=x;
         if(front==-1){
             front++;
         }
     }

     void pop(){
         if(back==-1 || front>back){
             cout<<"queue is empty";
             return;
         }
         front++;
     }

     int peek(){
        if(front==-1 || front>back){
             cout<<"queue is empty";
             return -1;
         }  
        return arr[front];
     }

     bool empty(){
         if(front==-1 || front>back){
             return true;
         } 
         return false;
     }
};

int main(){


    queue q;
    q.push(1);
    q.push(2);
    q.push(3);
    q.push(4);
    q.push(5);


    cout<<q.peek()<<endl;
    q.pop();

    cout<<q.peek()<<endl;
    q.pop();

    cout<<q.peek()<<endl;
    q.pop();

    cout<<q.peek()<<endl;
    q.pop();

    cout<<q.peek()<<endl;
    q.pop();

    cout<<q.empty()<<endl;

    return 0;
}