diff --git a/DSA_CPP/creatingDoublyLL.c b/DSA_CPP/creatingDoublyLL.c
new file mode 100644
index 00000000..7259ec9c
--- /dev/null
+++ b/DSA_CPP/creatingDoublyLL.c
@@ -0,0 +1,116 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef int itemType;
+
+//self referential structure
+typedef struct node
+{
+    itemType info;
+    struct node *link, *prev;
+}node;
+
+typedef struct List
+{
+    node *head, *tail;
+}List;
+
+node *createNode(itemType x)
+{
+    node *p;
+    p = (node *)malloc(1*sizeof(node));
+    if (p==NULL)
+    {
+        printf("Memory not allocated\n");
+        exit(1);
+    }
+    p->info = x;
+    p->link = NULL;
+    p->prev = NULL;
+    return p;
+}
+void show(List *lp)
+{
+    node *p;
+
+    p = lp->head;
+    printf("Linked list is: ");
+    while(p != NULL)
+    {
+        printf("%d---->", p->info);
+        p = p->link;
+    }
+    printf("NULL\n\n");
+}
+void showReverse(List *lp)
+{
+    node *p;
+
+    p = lp->tail;
+    printf("Linked list is: ");
+    while(p != NULL)
+    {
+        printf("%d---->", p->info);
+        p = p->prev;
+    }
+    printf("NULL\n\n");
+}
+
+void insertAtTail(List *lp, itemType x)
+{
+    node *p;
+
+    p = createNode(x);
+
+    if (lp->head == NULL)
+        lp->head = p;
+    else
+    {
+        lp->tail->link = p;
+        p->prev = lp->tail;
+    }
+    lp->tail = p;
+}
+
+void initialize(List *lp)
+{
+    lp->head = NULL;
+    lp->tail = NULL;
+}
+List *createList()
+{
+    List *lp;
+    itemType x;
+    int n, i;
+
+    //allocate space for head and tail
+    lp = (List *)malloc(sizeof(List));
+    if (lp==NULL)
+    {
+        printf("Memory not allocated\n");
+        exit(1);
+    }
+    initialize(lp);
+
+    printf("Enter count of items: ");
+    scanf("%d", &n);
+
+    srand(time(0));
+    for (i=0; i<n; ++i)
+    {
+        x = rand()%100;
+        insertAtTail(lp, x);
+    }
+    return lp;
+}
+
+int main()
+{
+    List *lp;
+
+    lp = createList();
+    show(lp);
+    showReverse(lp);
+
+    return 0;
+}
diff --git a/DSA_CPP/queueClass.cpp b/DSA_CPP/queueClass.cpp
new file mode 100644
index 00000000..70332477
--- /dev/null
+++ b/DSA_CPP/queueClass.cpp
@@ -0,0 +1,80 @@
+#include <iostream>
+
+using namespace std;
+
+typedef int itemType;
+
+class Queue
+{
+private:
+    int front, rear, count, max;
+    itemType *a;
+
+public:
+    Queue(int s=5)
+    {
+        initialize();
+        max = s;
+        a = new itemType[max];
+    }
+    initialize()
+    {
+        front = 0;
+        rear = -1;
+        count = 0;
+    }
+    int full()
+    {return count==max;}
+    int empty()
+    {return count==0;}
+
+    void addition(itemType x)
+    {
+        if (full())
+        {
+            cout<<"Queue overflow\n";
+            exit(1);
+        }
+        rear = (rear+1)%max;
+        a[rear] = x;
+        ++count;
+    }
+
+    itemType deletion()
+    {
+        if (empty())
+        {
+            cout<<"Queue underflow\n";
+            exit(2);
+        }
+        itemType x;
+        x = a[front];
+        front = (front+1)%max;
+        --count;
+        return x;
+    }
+    void show()
+    {}
+
+    //free the memory allocated in the constructor
+    ~Queue()
+    {delete a;}
+};
+
+int main()
+{
+    Queue q(4);
+    itemType x;
+
+    x=10; q.addition(x);
+    x=50; q.addition(x);
+    x=90; q.addition(x);
+    x=20; q.addition(x);
+    //x=10; q.addition(x);  //overflow
+
+    while (!q.empty())
+        cout<<"The deleted item is: "<<q.deletion()<<endl;
+
+    //x = q.deletion(); //underflow
+    return 0;
+}
diff --git a/DSA_CPP/shellSortToBeModified.c b/DSA_CPP/shellSortToBeModified.c
new file mode 100644
index 00000000..79c9fbf2
--- /dev/null
+++ b/DSA_CPP/shellSortToBeModified.c
@@ -0,0 +1,67 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define MAX 20
+typedef int itemType;
+
+void fill(itemType L[], int n);
+void show(itemType L[], int n);
+void shellSort(itemType L[], int n);
+
+int main()
+{
+    itemType list[MAX];
+    int n;
+
+    printf("Enter the current size of the list: ");
+    scanf("%d", &n);
+
+    fill(list, n);
+    show(list, n);
+    shellSort(list, n);
+    show(list, n);
+
+    return 0;
+}
+
+void shellSort(itemType L[], int n)
+{
+    int i, current, h;
+    itemType temp;
+
+    for(h=n/3+1; h>=1; h=h/3+1)
+    {
+        for (current=h; current<n; current+=h)
+        {
+            temp = L[current];
+            for (i=current-h; i>=0; i-=h)
+            {
+                if (L[i]>temp)
+                {
+                    L[i+h] = L[i];
+                    //show(L,n);
+                    //getch();
+                }
+                else
+                    break;
+            }
+            L[i+h] = temp;
+        }
+    }
+
+}
+void fill(itemType L[], int n)
+{
+    int i;
+    srand(time(0));
+    for (i=0; i<n; ++i)
+        L[i] = rand()%100;
+}
+void show(itemType L[], int n)
+{
+    int i;
+    printf("The list is: ");
+    for (i=0; i<n; ++i)
+        printf("%d  ", L[i]);
+    printf("\n\n");
+}