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Old 21-Jun-2005, 09:33
Krandygrl00 Krandygrl00 is offline
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linked list error message


in vb6 im getting an error message :
error C2955: 'list' : use of class template requires template argument list
d:\program files\microsoft visual studio\vc98\include\list(415) : see declaration of 'list'

and it points to this

CPP / C++ / C Code:
template<class Type>
ostream& operator<<(ostream& osObject, const linkedListType<Type>& list)
{
	nodeType<Type> *current; //pointer to traverse the list

	current = list.first;   //set current so that it points to 
					   //the first node
	while(current != NULL) //while more data to print
	{
	   osObject<<current->info<<" ";
	   current = current->link;
	}

	return osObject;
}

I dont understand this error at all everything looks correct in that function to me

here is my code

CPP / C++ / C Code:
#ifndef H_LinkedListType
#define H_LinkedListType

#include <iostream>
#include <list>
#include <algorithm>
#include <iterator>
#include <time.h>
#include <cassert>
using namespace std;

template <class Type>
struct nodeType
{
	Type info;
	nodeType<Type> *link;
	nodeType<Type> *back;
};
//------------------------------------------------------------------------
template<class Type>
class linkedListType
{
	friend ostream& operator<<(ostream&, const linkedListType<Type>&);

public:
    const linkedListType<Type>& operator=
          			      (const linkedListType<Type>&); 
		//Overload the assignment operator.
    void initializeList(); 
 		//Initializes the list to an empty state.
	    //Postcondition: first = NULL, last = NULL,
		//                count = 0
    bool isEmptyList();
 		//Function to determine whether the list is empty. 
		//Postcondition: Returns true if the list is empty;
		//               otherwise, returns false.

	int length();
		//Function to return the number of nodes in the 
		//list.
		//Postcondition: The value of count is returned.
    void destroyList();
 		//Function to delete all the nodes from the list.
  		//Postcondition: first = NULL, last = NULL, 
		//               count = 0
    Type front(); 
 		//Function to return the first element of the list.
 		//Precondition: The list must exist and must not be
		//empty.
  		//Postcondition: If the list is empty, then the 
 		//               program terminates; otherwise, 
	    //               the first element of the list is 
		//               returned.
    Type back(); 
       //Function to return the last element of the
       //list.
		//Precondition: The list must exist and must not
		//be empty.
		//Postcondition: If the list is empty, then the 
		//               program terminates; otherwise,
		//               the last element of the list is 
		//               returned.

   bool search(const Type& searchItem);
		//Function to determine whether searchItem is in 
		//the list.
		//Postcondition: Returns true if searchItem is found
		//               in the list; otherwise, it returns
		//               false.

    void insertFirst(const Type& newItem);
		//Function to insert newItem in the list.
		//Postcondition: first points to the new list 
		//                and newItem is inserted at the
		//                beginning of the list.

    void insertLast(const Type& newItem);
		//Function to return newItem at the end of the
		//list.
	    //Postcondition: first points to the new list, 
		//                newItem is inserted at the end
		//                of the list, and last points to
		//                the last node in the list.

    void deleteNode(const Type& deleteItem);
  		//Function to delete deleteItem from the list.
 		//Postcondition: If found, the node containing 
   		//               deleteItem is deleted from the 
		//                list, first points to the first
		//                node, and last points to the last 
		//                node of the updated list. 

    linkedListType(); 
   		//default constructor
 		//Initializes the list to an empty state.
 		//Postcondition: first = NULL, last = NULL, 
		//               count = 0 

    linkedListType(const linkedListType<Type>& otherList); 
         //copy constructor

    ~linkedListType();   
    	//destructor
   		//Deletes all the nodes from the list.
    	//Postcondition: The list object is destroyed.
	void reversePrint();
		//function to output the info contained in each node in reverse order
	void insertAt(int location, const Type& insertItem);
		//function to insert insert an item at location n where n is any value between 0 and 5000
	void printList();

protected:
    int count;		//variable to store the number of 
 					//elements in the list
    nodeType<Type> *first; //pointer to the first node of 
                           //the list
    nodeType<Type> *last;  //pointer to the last node of 
                           //the list 
private:
    void copyList(const linkedListType<Type>& otherList); 
		//Function to make a copy of otherList.
		//Postcondition: A copy of otherList is created 
		//               and assigned to this list.
};
//------------------------------------------------------------------------
template<class Type>
bool linkedListType<Type>::isEmptyList()
{
	return(first == NULL);
}

template<class Type>
linkedListType<Type>::linkedListType() // default constructor
{
	first = NULL;
	last = NULL;
	count = 0;
}

template<class Type>
void linkedListType<Type>::destroyList()
{
	nodeType<Type> *temp;   //pointer to deallocate the memory 
							//occupied by the node
	while(first != NULL)    //while there are nodes in the list
	{
	   temp = first;        //set temp to the current node
	   first = first->link; //advance first to the next node
	   delete temp;         //deallocate memory occupied by temp
	}

	last = NULL;	//initialize last to NULL; first has already
                   //been set to NULL by the while loop
 	count = 0;
}

	
template<class Type>
void linkedListType<Type>::initializeList()
{
	destroyList(); //if the list has any nodes, delete them
}

template<class Type>
int linkedListType<Type>::length()
{
 	return count;
}  // end length

template<class Type>
Type linkedListType<Type>::front()
{   
    assert(first != NULL);
   	return first->info; //return the info of the first node	
}//end front


template<class Type>
Type linkedListType<Type>::back()
{   
	 assert(last != NULL);
   	 return last->info; //return the info of the first node	
}//end back

template<class Type>
bool linkedListType<Type>::search(const Type& searchItem)
{
    nodeType<Type> *current; //pointer to traverse the list
    bool found;

    current = first; //set current to point to the 
                     //first node in the list
    found = false;   //set found to false

    while(current != NULL && !found)		//search the list
        if(current->info == searchItem)     //the item is found
           found = true;
        else
           current = current->link; //make current point 
                                    //to the next node
     
     return found;
}//end search

template<class Type>
void linkedListType<Type>::insertFirst(const Type& newItem)
{
	nodeType<Type> *newNode; //pointer to create the new node

	newNode = new nodeType<Type>; //create the new node

	assert(newNode != NULL);	//If unable to allocate memory, 
 								//terminate the program

	newNode->info = newItem; 	   //store the new item in the node
	newNode->link = first;        //insert newNode before first
	first = newNode;              //make first point to the 
                                 //actual first node
	count++; 			   //increment count

	if(last == NULL)   //if the list was empty, newNode is also 
                      //the last node in the list
		last = newNode;
}

template<class Type>
void linkedListType<Type>::insertLast(const Type& newItem)
{
	nodeType<Type> *newNode; //pointer to create the new node

	newNode = new nodeType<Type>; //create the new node

	assert(newNode != NULL);	//If unable to allocate memory, 
 							    //terminate the program

	newNode->info = newItem;      //store the new item in the node
	newNode->link = NULL;         //set the link field of newNode
         						//to NULL

	if(first == NULL)	//if the list is empty, newNode is 
     					//both the first and last node
	{
		first = newNode;
		last = newNode;
		count++;		//increment count
	}
	else			//the list is not empty, insert newNode after last
	{
		last->link = newNode; //insert newNode after last
		last = newNode;   //make last point to the actual last node
		count++;		//increment count
	}
}//end insertLast

template<class Type>
void linkedListType<Type>::deleteNode(const Type& deleteItem)
{
	nodeType<Type> *current; //pointer to traverse the list
	nodeType<Type> *trailCurrent; //pointer just before current
	bool found;

	if(first == NULL)    //Case 1; list is empty. 
		cerr<<"Can not delete from an empty list.\n";
	else
	{
		if(first->info == deleteItem) //Case 2 
		{
			current = first;
			first = first->link;
			count--;
			if(first == NULL)    //list has only one node
				last = NULL;
			delete current;
		}
		else  //search the list for the node with the given info
		{
			found = false;
			trailCurrent = first;   //set trailCurrent to point to
                                 //the first node
			current = first->link;  //set current to point to the 
    			   //second node
	
			while(current != NULL && !found)
			{
  				if(current->info != deleteItem) 
				{
					trailCurrent = current;
					current = current->link;
				}
				else
					found = true;
			} // end while

			if(found) //Case 3; if found, delete the node
			{
				trailCurrent->link = current->link;
				count--;

				if(last == current)      //node to be deleted was 
                                     //the last node
					last = trailCurrent;  //update the value of last

				delete current;  //delete the node from the list
			}
			else
				cout<<"Item to be deleted is not in the list."<<endl;
		} //end else
	} //end else
} //end deleteNode


	//Overloading the stream insertion operator
template<class Type>
ostream& operator<<(ostream& osObject, const linkedListType<Type>& list)
{
	nodeType<Type> *current; //pointer to traverse the list

	current = list.first;   //set current so that it points to 
					   //the first node
	while(current != NULL) //while more data to print
	{
	   osObject<<current->info<<" ";
	   current = current->link;
	}

	return osObject;
}

template<class Type>
linkedListType<Type>::~linkedListType() // destructor
{
	destroyList(); 
}//end destructor


template<class Type>
void linkedListType<Type>::copyList
            	      (const linkedListType<Type>& otherList) 
{
   nodeType<Type> *newNode; //pointer to create a node
   nodeType<Type> *current; //pointer to traverse the list

   if(first != NULL)	//if the list is nonempty, make it empty
	  destroyList();

   if(otherList.first == NULL) //otherList is empty
   {
		first = NULL;
		last = NULL;
 		count = 0;
   }
   else
   {
		current = otherList.first;  //current points to the 
									//list to be copied
		count = otherList.count;

			//copy the first node
		first = new nodeType<Type>;  //create the node

 		assert(first != NULL);

		first->info = current->info; //copy the info
		first->link = NULL;  	     //set the link field of 
									 //the node to NULL
		last = first;    		     //make last point to the 
            						 //first node
		current = current->link;     //make current point to  
           							 //the next node

			//copy the remaining list
		while(current != NULL)
		{
			newNode = new nodeType<Type>;  //create a node

			assert(newNode!= NULL);

			newNode->info = current->info;	//copy the info
			newNode->link = NULL;   	    //set the link of 
                                        //newNode to NULL
			last->link = newNode; 		//attach newNode after last
			last = newNode;   			//make last point to
										//the actual last node
			current = current->link;	//make current point to
       									//the next node
		}//end while
	}//end else
}//end copyList


	//copy constructor
template<class Type>
linkedListType<Type>::linkedListType
            	      (const linkedListType<Type>& otherList) 
{
	first = NULL;

	copyList(otherList);
	
}//end copy constructor

	//overload the assignment operator
template<class Type>
const linkedListType<Type>& linkedListType<Type>::operator=
   	 	 		(const linkedListType<Type>& otherList)
{ 
	if(this != &otherList) //avoid self-copy
		copyList(otherList);

	return *this; 
}
template<class Type>
void linkedListType<Type>::reversePrint()
{
	nodeType<Type> *current;	//pointer to traverse the list
	current = last;				//set current to point to the last node

	while(current != NULL)
	{
		cout << current ->info << " ";
		current = current->back;
	}//end while
}//end reversePrint
template<class Type>
void linkedListType<Type>::insertAt(int location, const Type& insertItem)
{
	if(location < 0 || location >= count)
		cerr << "The position is out of range." << endl;
	else
		if(length >= count)		//list is full
			cout << "cannot insert." << endl;
		else
		{
			for(int i = length; i > location; i--)
				list[i] = list[i - 1];
			list[location] = insertItem;

			length++;
		}
}
template<class Type>
void linkedListType<Type>::printList() 
{
	nodeType<Type> *current;
	current = first;
	while (current != NULL) 
	{
		cout << current->info << " ";
		current = current->link;
	}
	cout << endl;
}
#endif
//------------------------------------------------------------------------
int main()
{
     linkedListType<int> intList1;

     generate_n(intList1, 5000 , rand);
	
	cout << "Forward LIST1..." << endl;								//list1
	intList1.printList();

	intList1.reversePrint();
	cout << "Reversing LIST1..." << endl;							//reversing list
	intList1.printList();
	cout << endl;

	cout << "Inserting at POSITION..." << endl;						//position
	intList1.insertAt(4, 999);
	intList1.printList();
	cout << endl;

	cout << "Inserting at the BEGINNING of the list..." << endl;	//beginning
	intList1.insertFirst(0);
	intList1.printList();
	cout << endl;
	
	cout << "Inserting at the MIDDLE of the list..." << endl;		//middle
	intList1.insertAt(intList1.length() / 2, 555);
	intList1.printList();
	cout << endl;

	cout << "Inserting at the END of the list..." << endl;			//end
	intList1.insertLast(99);
	intList1.printList();
	cout << endl;

	cout << "Deleting at the BEGINNING of the list..." << endl;		//delete at beg.
	intList1.deleteNode(0);
	intList1.printList();
	cout << endl;

	cout << "Deleting at the MIDDLE of the list..." << endl;		//delete at midd.
	intList1.deleteNode(intList1.length() / 2);
	intList1.printList();
	cout << endl;

	cout << "Deleting at the END of the list..." << endl;			//delete at the end
	intList1.deleteNode(99);
	intList1.printList();
	cout << endl;
	
	return 0;
}
Last edited by LuciWiz : 21-Jun-2005 at 10:20. Reason: Please insert your C++ code between [c++] & [/c++] tags
  #2  
Old 21-Jun-2005, 13:21
QED's Avatar
QED QED is offline
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Posts: 231
QED is a jewel in the roughQED is a jewel in the roughQED is a jewel in the rough
The offending piece of code is probably is the following from your linkedListType class declaration:
CPP / C++ / C Code:
friend ostream& operator<<(ostream&, const linkedListType<Type>&);
I believe there are a couple of ways to fix this, one of which is:
CPP / C++ / C Code:
friend ostream& operator<< <>(ostream&, const linkedListType<Type>&);
Look carefully, because the '<' and '>' characters can get confusing. The problem arises from the fact that your friend declaration seems to declare a non-template function, while the function definition you use is clearly a template definition. The little '<>' after the function name tell the compiler that this is a template declaration. (Note that here the function name is operator <<)

Matthew
  #3  
Old 21-Jun-2005, 18:39
Krandygrl00 Krandygrl00 is offline
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Im getting errors still....from some reason vb6 doesnt like this...i really dont understand your post made sense but still not likeing it.....=(
  #4  
Old 21-Jun-2005, 19:05
QED's Avatar
QED QED is offline
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Join Date: Feb 2005
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Posts: 231
QED is a jewel in the roughQED is a jewel in the roughQED is a jewel in the rough
:-(
I will have access to VC6 tomorrow. Although I know that VC6 does not support several features of C++ templates, I am sure that there is a solution for your problem under that compiler version. I'll see what I can find. Until then, search around on Google for some clues.

Matthew
  #5  
Old 22-Jun-2005, 14:13
QED's Avatar
QED QED is offline
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Join Date: Feb 2005
Location: Hudson Valley, NY
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QED is a jewel in the roughQED is a jewel in the roughQED is a jewel in the rough
Okay... I think I can finally help.

The friend syntax you used in your original example actually works fine in VC6! However, it is non-standard (not much you can do about it if you must use VC6).
I finally did what I should have taken the time to do initially, which is compile your whole program as you posted it. The error message you posted results from your method insertAt, which attempts to use a variable list. Unfortunately, there is no variable named list is declared in that scope! Another problem, which is why you see that particular message instead of "undeclared variable", is that you are including the Standard header <list> and using the std namespace, so the compiler recognizes the name list as referring to the class std::list.

There are other errors in your code, such as the symbol length, again in the method insertAt. You use it as a variable, but the only length in scope is the method (that is, member function).

Try tackling some of these problems and I'll be happy to help if you come back with other specific questions/error messages.

Matthew
 
 

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