Not repeated elements in link list (help)

Question

lmastex 0 Newbie Poster

15 Years Ago

Hi.

I want my Insertion method in my link list class not to insert repeated elements. I have tried several ways but I have seriously ugly bugs in my code:

template <typename ListElement>
void List <ListElement>::Insert()
{
  NodePtr Ptr;
  Ptr = new Node;
  bool repeated = true;

if (Ptr == NULL)
  {
     cout << "Error: Insuficient Storage " << endl;
     exit(1);
  }
  
  cout << " Enter The Social Security Number of New Student: ";
  cin >> Ptr->Info.SSN;
  cout << "Enter The Age of This Student: ";
  cin >> Ptr->Info.Age;
 
	while( Ptr->Next != NULL)
	{
           if(Ptr->Info.Age == Ptr->Next->Info.Age)
             repeated = false;
             break; // This break is for not to add the element
             
             Ptr = Ptr->Next;
         
         
           }
  
Ptr->Next = Head;
  Head = Ptr;
  	
if(repeated = false)
 cout << "repetition just ocurred" << endl; // This is just 4 me to verified if the function works
 


	}

What do you think it is? Thanks

c++

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11 Replies
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Latest Post 15 Years Ago Latest Post by Laiq Ahmed

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Freaky_Chris 299 Master Poster

15 Years Ago

Use code tags please [code=cplusplus] [/code]
Also what exactly is the problem?

Chris

Freaky_Chris 299 Master Poster

15 Years Ago

Here is one method of doing it, get the Age from the user, loop through your linked list. If you find it don't add it to the list if you don't then when add it to the list

Chris

cikara21 37 Posting Whiz

15 Years Ago

Just call this..

bool sample::exist(NodePtr *p,int age)
{
   bool isexist=false;
   NodePtr *n_ptr = p;
   for(;n_ptr!=0;n_ptr=n_ptr->Next)
      if(n_ptr->Info.Age==age)
         isexist=true;
   return isexist;
)

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lmastex 0 Newbie Poster · Answer 1 · 2008-12-05T00:18:44+00:00

Sorry I forgot ( I remember I used them though) Anyways.
The problem is that when I make an insertion of an element, I don't want to insert a repeated element, so if I inserted (Age = 20) and then If I insert (Age = 20) my list should have only one person who Age is 20, i don't want two ages of 20 in my list. Insertion without repeating elements.

template <typename ListElement>
void List <ListElement>::Insert()
{
NodePtr Ptr;
Ptr = new Node;
bool repeated = true;

if (Ptr == NULL)
{
cout << "Error: Insuficient Storage " << endl;
exit(1);
}

cout << " Enter The Social Security Number of New Student: ";
cin >> Ptr->Info.SSN;
cout << "Enter The Age of This Student: ";
cin >> Ptr->Info.Age;

while( Ptr->Next != NULL)
{
if(Ptr->Info.Age == Ptr->Next->Info.Age)
repeated = false;
break; // This break is for not to add the element

Ptr = Ptr->Next;


}

Ptr->Next = Head;
Head = Ptr;

if(repeated = false)
cout << "repetition just ocurred" << endl; // This is just 4 me to verified if the function works



}

Laiq Ahmed 42 Junior Poster · Answer 2 · 2008-12-05T01:00:23+00:00

Sorry I forgot ( I remember I used them though) Anyways.
The problem is that when I make an insertion of an element, I don't want to insert a repeated element, so if I inserted (Age = 20) and then If I insert (Age = 20) my list should have only one person who Age is 20, i don't want two ages of 20 in my list. Insertion without repeating elements.
template <typename ListElement>
void List <ListElement>::Insert()
{
NodePtr Ptr;
Ptr = new Node;
bool repeated = true;

if (Ptr == NULL)
{
cout << "Error: Insuficient Storage " << endl;
exit(1);
}

cout << " Enter The Social Security Number of New Student: ";
cin >> Ptr->Info.SSN;
cout << "Enter The Age of This Student: ";
cin >> Ptr->Info.Age;

while( Ptr->Next != NULL)
{
if(Ptr->Info.Age == Ptr->Next->Info.Age)
repeated = false;
break; // This break is for not to add the element

Ptr = Ptr->Next;


}

Ptr->Next = Head;
Head = Ptr;

if(repeated = false)
cout << "repetition just ocurred" << endl; // This is just 4 me to verified if the function works



}

I've changed your code

template <typename ListElement>
void List <ListElement>::Insert()
{
NodePtr Ptr;
Ptr = new Node;
bool repeated = false;

  if (Ptr == NULL)
 {
    cout << "Error: Insuficient Storage " << endl;
    exit(1);
 }

  cout << " Enter The Social Security Number of New Student: ";
  cin >> Ptr->Info.SSN;
  cout << "Enter The Age of This Student: ";
  cin >> Ptr->Info.Age;

 while( Ptr->Next != NULL)
 {
      if(Ptr->Info.Age == Ptr->Next->Info.Age) {
          repeated = true; 
          break; 
     }
     // This break is for not to add the element
     Ptr = Ptr->Next;
  }

 if(repeated = false) {
    Ptr->Next = Head;
    Head = Ptr;
 }
  else { 
          delete Ptr;
          cout << "repetition just ocurred" << endl; // This is just 4 me to verified if the function works
   }

Hope Above idea helps

lmastex 0 Newbie Poster · Answer 3 · 2008-12-05T01:40:08+00:00

If there is a break in line 23 to stop the element to be added, then why is line 34 is a deletion?

(Im having problems with the code "cpp Syntax" changed)

Laiq Ahmed 42 Junior Poster · Answer 4 · 2008-12-05T01:42:58+00:00

because You allocated the element on Heap in the beginning and you should release its memory if its a repeated element otherwise you'd have a memory leak.

lmastex 0 Newbie Poster · Answer 5 · 2008-12-05T01:51:39+00:00

Oh ok I see. I don't know why but when I add an element (using this code) and press Enter, a windows error occur and the terminal closes. Any ideas?

Laiq Ahmed 42 Junior Poster · Answer 6 · 2008-12-05T02:05:28+00:00

Oh ok I see. I don't know why but when I add an element (using this code) and press Enter, a windows error occur and the terminal closes. Any ideas?

Yes! there are other mistakes in your code which I didn't touch :). while( Ptr->Next != NULL) should be replaced.

other misakes are there as well.

lmastex 0 Newbie Poster · Answer 7 · 2008-12-05T05:44:13+00:00

I replaced it to: while( Ptr != 0) But I still have the same problem.
I think I have to replace if(Ptr->Info.Age == Ptr->Next) but I don't find the right way.

Laiq Ahmed 42 Junior Poster · Answer 8 · 2008-12-05T15:48:57+00:00

I replaced it to: while( Ptr != 0) But I still have the same problem.
I think I have to replace if(Ptr->Info.Age == Ptr->Next) but I don't find the right way.

Here is a sample code, thanks for your efforts :).

template<class T>
class Node { 
	T _element;
	Node* _next;
public: 
	Node(const T& element, Node* next = 0) : _element(element), _next(next) {}

	T Element() const { return _element; }

	Node*& Next() {	return _next; }

};


template<class T>
class LinkList { 
	Node<T>* _head;

public:
	LinkList() : _head(0) {}
	bool Insert(const T& element);
	void PrintList() const;
};

template<class T>
bool LinkList<T>::Insert(const T& element) 
{
	
	if (!_head) {
		_head = new Node<T>(element);
		return true;
	}

	if (element == _head->Element ()) {
		return false;
	}

	// Temporary pointer to head.
	Node<T>* _headIter = _head;
	bool bRepeated = false;
	while (_headIter->Next()) {
		if (element == _headIter->Element()) {
			bRepeated = true;
		}
		_headIter = _headIter->Next();
	}
	
	if (bRepeated) {
		cout<<" Repeated: element is : "<< element <<endl;
	}
	else {
		_headIter->Next() = new Node<T>(element);
	}

	return true;
}

template<class T> 
void LinkList<T>::PrintList() const
{
	Node<T>* _headIter = _head;
	while (_headIter) {
		cout<<"The element is : " << _headIter->Element()<<endl;
		_headIter = _headIter->Next();
	}
}

try to acheive this task its interesting one
there is a link list with repeated elements remove all the repeated elements :).

Not repeated elements in link list (help)

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