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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3.  
  4. template <typename Type>
  5. class Node{
  6. public:
  7.     Type data;
  8.     Node<Type>* next;
  9.  
  10.     // Constructor
  11.     Node(const Type& value){
  12.         this->data = value;
  13.         this->next = nullptr;
  14.     }
  15. };
  16.  
  17. template <typename Type>
  18. class Queue{
  19. private:
  20.     Node<Type>* front;
  21.     Node<Type>* rear;
  22.     int maxSize, length;
  23.  
  24. public:
  25.     Queue(){
  26.         front = nullptr;
  27.         rear = nullptr;
  28.         length = 0;
  29.         maxSize = 10000;
  30.     }
  31.  
  32.     /// check if queue is full
  33.     bool isFull(){
  34.         if(length == maxSize)
  35.             return true;
  36.         else
  37.             return false;
  38.     }
  39.  
  40.     /// check if queue is empty
  41.     bool isEmpty(){
  42.         if(length == 0)
  43.             return true;
  44.         else
  45.             return false;
  46.     }
  47.  
  48.     /// get front element
  49.     Type getFront(){
  50.         if(isEmpty()){
  51.             throw runtime_error("Queue is empty");
  52.         }
  53.         return front->data;
  54.     }
  55.  
  56.     /// get rear element
  57.     Type getRear(){
  58.         if(isEmpty()){
  59.             throw runtime_error("Queue is empty");
  60.         }
  61.         return rear->data;
  62.     }
  63.  
  64.     /// get length
  65.     int getLength(){
  66.         return length;
  67.     }
  68.  
  69.     /// insert (enqueue)
  70.     void enqueue(Type key){
  71.         if(isFull()){
  72.             throw runtime_error("Queue overflow!!!");
  73.         }
  74.  
  75.         Node<Type>* newNode = new Node<Type>(key);
  76.  
  77.         if(isEmpty()){
  78.             front = rear = newNode;
  79.         }
  80.         else{
  81.             rear->next = newNode;
  82.             rear = newNode;
  83.         }
  84.  
  85.         length++;
  86.     }
  87.  
  88.     /// delete (dequeue)
  89.     void dequeue(){
  90.         if(isEmpty()){
  91.             throw runtime_error("Queue underflow!!!");
  92.         }
  93.  
  94.         Node<Type>* temp = front;
  95.         front = front->next;
  96.         delete temp;
  97.         length--;
  98.  
  99.         if(front == nullptr){   // if queue becomes empty
  100.             rear = nullptr;
  101.         }
  102.     }
  103.  
  104.     /// destructor
  105.     ~Queue(){
  106.         while(!isEmpty()){
  107.             dequeue();
  108.         }
  109.     }
  110. };
  111.  
  112. int main()
  113. {
  114.     Queue<char> q1;
  115.  
  116.     q1.enqueue('a');
  117.     q1.enqueue('b');
  118.     q1.enqueue('c');
  119.  
  120.     cout << "Length: " << q1.getLength()
  121.          << " Front: " << q1.getFront()
  122.          << " Rear: " << q1.getRear() << endl;
  123.  
  124.     q1.dequeue();
  125.  
  126.     cout << "After Dequeue -> Front: " << q1.getFront() << endl;
  127.  
  128.     return 0;
  129. }
Success #stdin #stdout 0.01s 5320KB
comments (?)
stdin
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Standard input is empty
stdout
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Length: 3 Front: a Rear: c
After Dequeue -> Front: b
https://ideone.com/xhweZR
language:
C++ (gcc 8.3)
created:
1 hour ago
visibility:
public

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