problème de template

**Linu6** · 02/07/2008, 19h50

voila j'ai un code qui à mes yeux est parfait mais j'ai quand même deux erreurs de compilation.

voici le code

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#include<iostream>
 
using namespace std;
 
template<class T>class List
{
 // Attributes
 public:
	  // Implementation
 List()
{
  // initializes the list object for the first time
 
  _first_node = NULL;
  _number_of_nodes = 0;
}
  ~List();
 
  class invalid_position {};
  class out_of_memory {};
    // supported exceptions
  int get_number_of_items() const;
    // returns the list size
 
 // Operations
  void add(T* item);
    // add the specified item at the end of list
 
  void add(int at_position, T* item);
    // add the specified item at specified position
 
  void remove(int at_position);
    // remove and deletes the item stored at specified position
 
  T* get_item(int at_position);
    // returns the item stored at specified position
 
 
 
 
 protected:
  class T_Node
  {
  public:
    T_Node(T* item, T_Node* next_node)
    {
      _item = item;
      _next_node = next_node;
    }
 
    ~T_Node()
    {
      delete _item;
    }
 
    T* _item;
    T_Node* _next_node;
  };
 
  public:
 
    // this class is used internally to implement a single linked list
     T_Node* _first_node;
    // first node of the linked list
 
  int _number_of_nodes;
    // number of items stored in list
 
  T_Node* find_node(int node_position) ;
    // helper function to retrieve an indexed node
 
};
 
 
 
 
template<class T>List::~List()
{
  // deletes all stored items
 
  while (_number_of_nodes > 0)
    remove(0);
}
 
template<class T>inline int List::get_number_of_items()
{
  // returns list size
 
  return _number_of_nodes;
}
 
template<class T>inline void List::add(T* item)
{
  // adds an item at list tail
 
  add(_number_of_nodes, item);
}
 
template <class T> void List::add(int at_position, T* item)
{
  // adds an item at specified position
  // throws an out_of_memory exception in case of low system resources
  //  or an invalid_position if insertion at specified position is 
  //  impossible
 
  if (at_position == 0)
  {
    _first_node = new T_Node(item, NULL);
 
    if (_first_node == NULL)
      throw out_of_memory();
  }
  else
  {
    T_Node* previous_node = find_node(at_position - 1);
    // NOTE: find_node() can throw an invalid_position exception
 
    T_Node* next_node = previous_node->_next_node;
 
    previous_node->_next_node = new T_Node(item, next_node);
 
    if (previous_node->_next_node == NULL)
      throw out_of_memory();
  }
 
  _number_of_nodes++;
}
 
template <class T> void List::remove(int at_position)
{
  // removes and deletes the item indexed by the at_position value
  // throws an invalid_position if no item is available at specified
  //  position
 
  T_Node* node_to_delete;
 
  if (at_position == 0)
  {
    node_to_delete = _first_node;
    _first_node = node_to_delete->_next_node;
  }
  else
  {
    T_Node* previous_node = find_node(at_position - 1);
    // NOTE: find_node() can throw an invalid_position exception
 
    node_to_delete = previous_node->_next_node;
    previous_node->_next_node = node_to_delete->_next_node;
  }
 
  delete node_to_delete;
  _number_of_nodes--;
}
 
template<class T> inline T* List::get_item(int at_position) const
{
  // returns the requested item
  // throws an invalid_position if no item is available at specified
  //  position
 
  T_Node* node = find_node(at_position);
  return node->_item;
}
 
template <class T>List::T_Node* List::find_node(int node_position) const
{
  // searches (by index) a node in the internal single linked list
  // throws an invalid_position exception if no item found
 
  if (node_position < 0)
    throw invalid_position();
 
  T_Node* node = _first_node;
  int node_index = 0;
 
  while (node_index < node_position)
  {
    if (node == NULL)
      throw invalid_position();
 
    node = node->_next_node;
    node_index++;
  }
 
  return node;
}
 
int main()
{
 
}

et voici les erreurs

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1
2
xxx00L.cpp:77: error: syntax error before `::' token
xxx00L.cpp:78: confused by earlier errors, bailing out

**Alp** · 02/07/2008, 19h52

Tu pourrais nous montrer les lignes concernées s'il te plaît ? Je ne me sens pas trop de compter les lignes

**Linu6** · 02/07/2008, 19h55

c'est au niveau du destructeur de list que ça coince

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template<class T>List::~List()
{
  // deletes all stored items
 
  while (_number_of_nodes > 0)
    remove(0);
}

**Alp** · 02/07/2008, 19h56

Essaye :

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template<class T>
List<T>::~List()
{
  // deletes all stored items
 
  while (_number_of_nodes > 0)
    remove(0);
}

(et pareil pour le reste)

**Linu6** · 02/07/2008, 22h52

RE

voici le code corrigé, mais il reste encore un défaut.

Ainsi, lorsque je passe à add() un pointeur sur int j'obtiens à la sortie la valeur escomptée.

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int* a = new int(10);
 
	l.add(a);
 
 
	for (int i = 0; i < l.get_number_of_items(); i++)
	{
		int v = *l.get_item(i);
		cout << v << " ";
	}

mais quand il s'agit d'un pointeur sur char j'obtiens une valeur numérique et non une chaine.

p.s.

et voici le premier code corrigé:

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#ifndef LISTE_H
#define LISTE_H
 
template <class T> 
class List
{
 // Attributes
 public:
	int get_number_of_items() const;
		// returns the list size
 
 // Operations
 public:
	void add(T* item);
 
		// add the specified item at the end of list
 
	void add(int at_position, T* item);
		// add the specified item at specified position
 
	void remove(int at_position);
		// remove and deletes the item stored at specified position
 
	T* get_item(int at_position) const;
		// returns the item stored at specified position
 
 // Implementation
 public:
	List();
	~List();
 
	class invalid_position {};
	class out_of_memory {};
		// supported exceptions
 
 private:
	class T_Node
	{
	public:
		T_Node(T* item, T_Node* next_node)
		{
			_item = item;
			_next_node = next_node;
		}
 
		~T_Node()
		{
			delete _item;
		}
 
		T* _item;
		T_Node* _next_node;
	};
		// this class is used internally to implement a single linked list
 
	T_Node* _first_node;
		// first node of the linked list
 
	int _number_of_nodes;
		// number of items stored in list
 
	T_Node* find_node(int node_position) const;
		// helper function to retrieve an indexed node
};
 
/////////////////////////////////////////////////////////////////////////////
 
template <class T> 
List<T>::List()
{
	// initializes the list object for the first time
 
	_first_node = NULL;
	_number_of_nodes = 0;
}
 
template <class T>
List<T>::~List()
{
	// deletes all stored items
 
	while (_number_of_nodes > 0)
		remove(0);
}
 
template <class T> 
inline int List<T>::get_number_of_items() const
{
	// returns list size
 
	return _number_of_nodes;
}
 
 
template <class T>
inline void List<T>::add(T* item)
{
	// adds an item at list tail
 
	add(_number_of_nodes, item);
}
 
 
template <class T> 
void List<T>::add(int at_position, T* item)
{
	// adds an item at specified position
	// throws an out_of_memory exception in case of low system resources
	//  or an invalid_position if insertion at specified position is 
	//  impossible
 
	if (at_position == 0)
	{
		_first_node = new T_Node(item, NULL);
 
		if (_first_node == NULL)
			throw out_of_memory();
	}
	else
	{
		T_Node* previous_node = find_node(at_position - 1);
		// NOTE: find_node() can throw an invalid_position exception
 
		T_Node* next_node = previous_node->_next_node;
 
		previous_node->_next_node = new T_Node(item, next_node);
 
		if (previous_node->_next_node == NULL)
			throw out_of_memory();
	}
 
	_number_of_nodes++;
}
 
template <class T> 
void List<T>::remove(int at_position)
{
	// removes and deletes the item indexed by the at_position value
	// throws an invalid_position if no item is available at specified
	//  position
 
	T_Node* node_to_delete;
 
	if (at_position == 0)
	{
		node_to_delete = _first_node;
		_first_node = node_to_delete->_next_node;
	}
	else
	{
		T_Node* previous_node = find_node(at_position - 1);
		// NOTE: find_node() can throw an invalid_position exception
 
		node_to_delete = previous_node->_next_node;
		previous_node->_next_node = node_to_delete->_next_node;
	}
 
	delete node_to_delete;
	_number_of_nodes--;
}
 
template <class T>
inline T* List<T>::get_item(int at_position) const
{
	// returns the requested item
	// throws an invalid_position if no item is available at specified
	//  position
 
	T_Node* node = find_node(at_position);
	return node->_item;
}
 
template <class T>
List<T>::T_Node* List<T>::find_node(int node_position) const
{
	// searches (by index) a node in the internal single linked list
	// throws an invalid_position exception if no item found
 
	if (node_position < 0)
		throw invalid_position();
 
	T_Node* node = _first_node;
	int node_index = 0;
 
	while (node_index < node_position)
	{
		if (node == NULL)
			throw invalid_position();
 
		node = node->_next_node;
		node_index++;
	}
 
	return node;
}
 
#endif

problème de template

Langage C++

Vue hybride

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