added circularqueue

circularqueue.cpp

@@ -0,0 +1,101 @@
+#include <iostream>
+#include <cstdlib>
+
+template <class T>
+class circularqueue
+{
+    int front;
+    int rear;
+    T* array;
+    int n;
+public:
+    circularqueue()
+    {
+        std::cout <<"Enter the size of queue"<< std::endl;
+        std::cin >> n;
+        array = new T[n];
+        front = -1;
+        rear = -1;
+    }
+
+    void enqueue(T data)
+    {
+        if((front == 0 && rear == n - 1) || rear == front - 1)
+        {
+            std::cout << "Overflow!!" <<std::endl;
+        }
+        else if(front == -1)
+        {
+            front++;
+            rear++;
+            array[rear] = data;
+        }
+        else
+        {
+            if(front > 0 && rear == n)
+            {
+                rear = 0;
+                array[rear] = data;
+            }
+            else
+            {
+                rear++;
+                array[rear] = data;
+            }
+        }
+    }
+
+    T dequeue()
+    {
+        T data;
+        if(front == -1)
+        {
+            std::cout <<"Queue is empty" <<std::endl;
+            exit(0);
+        }
+
+        data = array[front];
+
+        if(front == rear)
+        {
+            front = rear = -1;
+        }
+        else
+        {
+            if(front = n-1) front = 0;
+            else front++;
+        }
+        return data;
+    }
+
+    void display()
+    {
+        if(front == -1)
+        {
+            std::cout <<"Queue is empty!!" <<std::endl;
+        }
+        else
+        {
+            int i = front;
+            while(i != rear)
+            {
+                std::cout <<array[i]<< "  ";
+                i++;
+            }
+            std::cout <<array[i]<< std::endl;
+
+        }
+    }
+};
+
+
+int main()
+{
+    circularqueue<int> q;
+    q.enqueue(2);
+    q.display();
+    q.dequeue();
+    q.display();
+
+    return 0;
+}