In this queue code my Array size is 5 but I can insert more than 5 element, how?

Question

This is a code for queue. my array size is 5 but I am able to insert more than 5 element and also can print all of them. how it is working?

#include <iostream>
#include <stdlib.h>

using namespace std;

int front=0, rear=-1;
int queue_array[5];

void enqueue(int a){
   if(front>4){
      cout<< "queue overflow" << endl;
      return;
   }
   rear++;
   queue_array[rear] = a;
   cout << "Inserted" << a << endl;
}

void dequeue(){
   if(front > rear){
      cout << "queue underflow" << endl;
      return;
   }
   int temp = queue_array[front];
   for(int i=1;i<=rear;i++){
      queue_array[i-1] = queue_array[i];
   }
   rear--;
   cout << "popped: " << temp << endl;
}

void display(){
   if(front>rear) cout << "Queue empty" << endl;
   for(int i=0; i<=rear; i++){
      cout << queue_array[i] << " " ;
   }
}

int main(){
   int element;

   while(1){
      cout << "\n1.Enqueue \n2.Dequeue\n3.Display \n4. Exit \n Enter your choice: ";
      cin >> element;

      switch(element){
         case 1: cin >> element;
                 enqueue(element);
                 break;

         case 2:
                 dequeue();
                 break;
         case 3:
                 display();
                 break;
         case 4:
                 exit(0);
      }

   }
   return 0;
}

Also queue all operation is working fine. What is the reason for that? Thanks in advance.