SinglyLinkedListNode *new_node = new SinglyLinkedListNode(data); new_node->data = data; new_node->next = NULL;

SinglyLinkedListNode *ptr;

if(head == NULL)
{
    head = new_node;
    return head;
}
else
{
    ptr = head;
    while(ptr->next != NULL)
    {
        ptr = ptr->next;
    }
    ptr->next = new_node;
    new_node->next = NULL;

    return head;    
}