Entities essential for Array Representation of Queue - Data Structure

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• Nirja Shah   -Posted on 16 Nov 15
  For an Array Representation of a Queue, the following points are necessary.
  - An array to hold queue elements
  - A variable to hold the index of front element
  - A variable to hold the index of rear element
  Consider a simple example.
  class Queue
  {
     int front,rear,size,i,item;
    int ∗que;
  public:
    Queue()
  {
     front=rear= -1;
     cout << "Enter the size of queue\t\t";
     cin >> size;
     que=new int[size];
  }
    void insert()
  {
     if(rear==size-1)
    {
    cout<< "queue is Full";
    }
   else
    {
     cout<< "Enter the "<< size << " item\n";
     for(i=0;i<size;i++)
      {
     cin>> item;
     rear++;
     que[rear]=item;
      }
    if(front==-1)
     front++;
    }
  }
  void deleteItem()
  {
     if( front==-1 || front==rear+1)
    {
     cout<< "queue is empty";
    }
  else
    {
     cout << "The deleted item is "<< que[front] << endl;
     front++;
    }
  }
  void display()
    {
     if(front==-1||front==rear+1)
    {
     cout << "queue is empty";
    }
  else
     {
      for(i=front;i<=rear;i++)
    {
     cout << que[i] << "\t\t";
    }
     }
    }
  };
  
  int main()
  {
     Queue obj;
     int choice;
  do
    {
      cout << "Enter 1. for Insert\n";
      cout << "Enter 2. for Delete\n";
      cout << "Enter 3. for showItem\n";
      cout << "Enter 4. for Exit\n";
      cout << "Enter you choice\n";
      cin >> choice;
    switch(choice)
   {
      case 1:
     obj.insert();
     break;
      case 2:
     obj.deleteItem();
     break;
      case 3:
     obj.display();
     break;
      case 4:
     break;
      default:
     cout<<"Wrong choice\n";
     break;
     }
   }
     while(choice < 4);
     return 0;
  }

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