Add a simple queue class

data_structure/queue/test_queue.cpp

@@ -0,0 +1,38 @@
+#include <iostream>
+#include <string>
+#include "queue.h"
+#include "queue.cpp"
+
+using namespace std;
+
+int main()
+{
+    queue<string> q;
+    cout << "---------------------- Test construct ----------------------" << endl;
+    q.display();
+    cout << "---------------------- Test isEmptyQueue ----------------------" << endl;
+    if(q.isEmptyQueue())
+        cout << "PASS" <<endl;
+    else
+        cout << "FAIL" <<endl;
+    cout << "---------------------- Test enQueue ----------------------" << endl;
+    cout << "After Hai, Jeff, Tom, Jkingston go into queue: "<<endl;
+    q.enQueue("Hai");
+    q.enQueue("Jeff");
+    q.enQueue("Tom");
+    q.enQueue("Jkingston");
+    q.display();
+    cout << "---------------------- Test front ----------------------" << endl;
+    string value = q.front();
+    if (value == "Hai")
+        cout << "PASS" <<endl;
+    else
+        cout << "FAIL" <<endl;
+    cout << "---------------------- Test deQueue ----------------------" << endl;
+    q.display();
+    q.deQueue();
+    q.deQueue();
+    cout << "After Hai, Jeff left the queue: "<< endl;
+    q.display();
+    return 0;
+}