Create Linked list - C++ Data Structure

Description

Create Linked list
Demo Code

                                                            
#include <iostream> 
                                                             
enum { kIsSmaller, kIsLarger, kIsSame }; 
                                                             
class Data { /* www .  j av  a  2s .co m*/
public: 
    Data(int newVal):value(newVal) {} 
    ~Data() {} 
    int compare(const Data&); 
    void show() { std::cout << value << "\n"; } 
private: 
    int value; 
}; 
                                                             
int Data::compare(const Data& otherData) 
{ 
    if (value < otherData.value) 
            return kIsSmaller; 
    if (value > otherData.value) 
            return kIsLarger; 
    else 
        return kIsSame; 
} 
                                                             
// forward class declarations 
class Node; 
class HeadNode; 
class TailNode; 
class InternalNode; 
                                                             
class Node { 
public: 
    Node() {} 
    virtual ~Node() {} 
    virtual Node* insert(Data* data) = 0; 
    virtual void show() = 0; 
private: 
}; 
                                                             
// A node to hold objects of type Data. 
class InternalNode : public Node 
{ 
public: 
    InternalNode(Data* data, Node* next); 
    virtual ~InternalNode() { delete next; delete data; } 
    virtual Node* insert(Data* data); 
    virtual void show() 
          { data->show(); next->show(); } // delegate! 
                                                             
private: 
    Data* data;  // the data itself 
    Node* next;  // points to next node in the linked list 
}; 
                                                             
// a simple constructor 
InternalNode::InternalNode(Data* newData, Node* newNext): 
data(newData), next(newNext) 
{ 
} 
                                                             
Node* InternalNode::insert(Data* otherData) { 
    // is the new object bigger or smaller than me? 
    int result = data->compare(*otherData); 
                                                             
    switch (result) 
    { 
    case kIsSame:         // fall through 
    case kIsLarger:    // new data comes before me 
          { 
              InternalNode* dataNode = 
                  new InternalNode(otherData, this); 
              return dataNode; 
          } 
     case kIsSmaller: 
         next = next->insert(otherData); 
          return this; 
    } 
    return this; // appease the compiler 
} 
                                                             
// The last node in the list 
class TailNode : public Node 
{ 
public: 
    TailNode() {} 
    virtual ~TailNode() {} 
    virtual Node* insert(Data* data); 
    virtual void show() {} 
private: 
}; 
                                                             
Node* TailNode::insert(Data* data) 
{ 
    InternalNode* dataNode = new InternalNode(data, this); 
    return dataNode; 
} 
                                                             
class HeadNode : public Node { 
public: 
    HeadNode(); 
    virtual ~HeadNode() { delete next; } 
    virtual Node* insert(Data* data); 
    virtual void show() { next->show(); } 
private: 
    Node* next; 
}; 
                                                             
// The first node in the list, which creates the tail 
HeadNode::HeadNode() 
{ 
    next = new TailNode; 
} 
Node* HeadNode::insert(Data* data) { 
    next = next->insert(data); 
    return this; 
} 
class LinkedList { 
public: 
    LinkedList(); 
    ~LinkedList() { delete head; } 
    void insert(Data* data); 
    void showAll() { head->show(); } 
private: 
    HeadNode* head; 
}; 
                                                             
LinkedList::LinkedList() { 
    head = new HeadNode; 
} 
                                                             
// Delegate to a head node 
void LinkedList::insert(Data* pData) 
{ 
    head->insert(pData); 
} 
                                                             
// put all these classes to the test 
int main() 
{ 
    Data* pData; 
    int val; 
    LinkedList ll; 
                                                             
    // store user values in a linked list 
    while (true) 
    { 
         std::cout << "What value (0 to stop)? "; 
         std::cin >> val; 
         if (!val) 
              break; 
         pData = new Data(val); 
         ll.insert(pData); 
   } 
                                                             
   // display the list 
   ll.showAll(); 
   return 0; 
}
Create Linked list - C++ Data Structure

Description

Demo Code

Result

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