Add a simple queue class

data_structure/queue/queue.cpp

@@ -0,0 +1,90 @@
+#include <iostream>
+#include <assert.h>
+#include "queue.h"
+
+using namespace std;
+
+/* Default constructor*/
+template <class Kind>
+queue<Kind>::queue()
+{
+    queueFront = NULL;
+    queueRear = NULL;
+    size = 0;
+}
+
+/* Destructor */
+template <class Kind>
+queue<Kind>::~queue()
+{
+}
+
+/* Display for testing */
+template <class Kind>
+void queue<Kind>::display()
+{
+    node<Kind> *current = queueFront;
+    cout << "Front --> ";
+    while(current != NULL) {
+        cout<<current->data<< "    ";
+        current = current -> next;
+    }
+    cout <<endl;
+    cout << "Size of queue: " << size << endl;
+}
+
+/* Determine whether the queue is empty */
+template <class Kind>
+bool queue<Kind>::isEmptyQueue()
+{
+    return (queueFront == NULL);
+}
+
+/* Clear queue */
+template <class Kind>
+void queue<Kind>::clear()
+{
+    queueFront = NULL;
+}
+
+/* Add new item to the queue */
+template <class Kind>
+void queue<Kind>::enQueue(Kind item)
+{
+    node<Kind> *newNode;
+    newNode = new node<Kind>;
+    newNode->data = item;
+    newNode->next = NULL;
+    if (queueFront == NULL) {
+        queueFront = newNode;
+        queueRear = newNode;
+    } else {
+        queueRear->next = newNode;
+        queueRear = queueRear->next;
+    }
+    size++;
+}
+
+/* Return the top element of the queue */
+template <class Kind>
+Kind queue<Kind>::front()
+{
+    assert(queueFront != NULL);
+    return queueFront->data;
+}
+
+/* Remove the element of the queue */
+template <class Kind>
+void queue<Kind>::deQueue()
+{
+    node<Kind> *temp;
+    if(!isEmptyQueue()) {
+        temp = queueFront;
+        queueFront = queueFront->next;
+        delete temp;
+        size--;
+    } else {
+        cout << "Queue is empty !" << endl;
+    }
+}
+