Implementation of circular Queue using linked list and Array in c++

CircularQueueArray.cpp

/*implementation of circular queue using array */
#include<iostream>
using namespace std;

  int front=-1,rear=-1;
  int size=0;


void createQueue(){
 cout<<"How many Element you want to create in Queue:: ";
 cin>>size;
}

int *Queue = new int[size];

void insert(int val){
 if ((front == 0 && rear == size-1) || (front == rear+1)) {
        cout<<"Overflow error\n";
        return;
 }
  if(front==-1){
    front=0;
    rear=0;
  }else{
    if(rear==size-1)
    rear= 0;
    else
    rear=rear+1;
  }
  Queue[rear]=val;
}

void deleteQ(){
  if(front==-1){
    cout<<"Underflow error\n";
    return;
  }
  cout<<"Element deleted from queue is : "<<Queue[front]<<endl;

  if(front==rear){
    front=-1;
    rear=-1;
  }else{
    if(front==size-1)
    front=0;
    else
    front+=1;
  }

}


void display(){
  int f = front, r = rear;
     if (front == -1) {
      cout<<"Queue is empty"<<endl;
      return;
     }
   cout<<"Queue elements are :\n";

   if (f <= r) {
      while (f <= r){
         cout<<Queue[f]<<" ";
         f++;
      }
   }else{
     while (f <= size - 1) {
         cout<<Queue[f]<<" ";
         f++;
      }
      f = 0;
      while (f <= r) {
         cout<<Queue[f]<<" ";
         f++;
      }
   }

}




int main(){
    createQueue();
   int ch, val;
   cout<<"1)Insert\n";
   cout<<"2)Delete\n";
   cout<<"3)Display\n";
   cout<<"4)Exit\n";

   do{
    cout<<"\nEnter choice : "<<endl;
    cin>>ch;

   switch(ch) {
         case 1:
         cout<<"\nInput for insertion: "<<endl;
         cin>>val;
         insert(val);
         break;

         case 2:
         deleteQ();
         break;

         case 3:
         display();
         break;

         case 4:
         cout<<"Exit\n";
         break;
         default: cout<<"Incorrect!\n";
      }
   } while(ch != 4);

return 0;
}

CircularQueueLinkedList.cpp

/*implementation of circular queue using linked list */
#include<iostream>
#include<cstdlib>
using namespace std;

 typedef struct OurQueue{
   int data;
   struct OurQueue *next;
 }node;

 node * createQueue(){
   node * front=NULL,*rear=NULL;
   int n, data;
   cout<<("How many Element you want to create in Queue:: ");
   cin>>n;
   int i=0;
   while(i<=(n-1)){
         cout<<"Enter data: ";
         cin>>data;
         node *newNode = (node *)malloc(sizeof(node));
         newNode->data = data;
    if(i==0){
         newNode->next = NULL;
         rear = newNode;
         front=newNode;
    }else{
			newNode->next=front;
			rear->next=newNode;
			rear = newNode;
    }
    ++i;
   }
   return rear;
 }

 void enqueue(node **rear,int data){
	node *newNode = (node *)malloc(sizeof(node));
	newNode->data = data;
	if(!(*rear)){
		newNode->next=NULL;
		*rear = newNode;
		return;
	}
	node *temp = *rear;
	if(!(*rear)->next){
		newNode->next = temp;
	}else{
		newNode->next = temp->next;
	}
	temp->next = newNode;
	*rear = newNode;
 }


int dequeue(node *rear){
	int data;
	if(!rear){
		cout<<("\nNO ITEMS IN THE QUEUE\n");
		return 0;
	}
	if(!rear->next){
		data = rear->data;
		free(rear);
		return data;
	}
	node *temp = rear->next;
	data = temp->data;
	rear->next = temp->next;
	free(temp);
	return data;
}



void display(node *rear, node *front){
	if(!rear){
		cout<<("\nNOTHING TO DISPLAY\n");
		return;
	}
	node *temp = front;
	if(!rear->next){
		cout<<rear->data<<" ";
		return;
	}
	if(temp!=rear){
		cout<<temp->data<<" ";
		display(rear, temp->next);
	}else{
		cout<<temp->data<<" ";
	}
}

int main(){
	node *rear = createQueue();
	display(rear,rear->next);
	enqueue(&rear,99);
	cout<<"\nAfter Adding item"<<endl;
	display(rear,rear->next);
	int data = dequeue(rear);
	cout<<"\nAfter Deleting item: "<<data<<endl;
	display(rear,rear->next);
	return 0;
return 0;
}