Linking error using a class list.

[CQ75]

I recieved the error

"1>List.obj : error LNK2019: unresolved external symbol "public: void __thiscall list::resetlist(void)" (?resetlist@list@@QAEXXZ) referenced in function _main"

for every single function contained in my class named "list" in my .h file when I tried to build the solution. It says "LNK", which I assume means a link error.

I don't know why, it seems like I did everything alright.

here's my .h file

/*

SPEC file. This file gives the specifications of a list data type. 

*/

#include <string> 

const int maxsize = 100; // maximum number of components.


typedef int itemtype; 

// type of each component... an int every time? how? 

//Because the functions who actually need the type of data all accept the data in the database; ints.

class list
{
public:
	list();

	// constructor, defined in the .cpp file, it makes an empty list.

	void insert(itemtype item);
	
	// if list is not full (that item doesn't take up the 100th space), item is in the list and LENGTH of list increases

	// where length is the number of spaces used

	void deleteitem(itemtype item); // "delete" is a reserved word

	// a given item is removed from the list, is the length subtracted by one? I'm not sure.... I think that's assumed.

	void resetlist();
	// the current position is reset to the first position.

	itemtype getnextitem();
	
	// resetlist() is called if an insert or delete has happened
	// hasnext() needs to run to tell it if there is something coming after the current value.

	bool hasnext() const;

	// tells if there is an entry after the current one in the list.

	bool isempty() const;
	
	// returns true if the list is empty

	bool isfull() const;

	// returns true if the list is full

	bool isthere (itemtype itemname) const;

	// returns true if an item of type _itemtype_ of value _itemname_ is in the list.

	int getlength() const;

	// returns length of list.

private: // why does this need to be private?

	int length;
	int currentpos;
	itemtype data[maxsize]; // the array of length maxsize = 100

};

and my .cpp file

// it reads the temperatures from a file and ignores duplicates. It ignores high temperatures and deletes only 1337.


#include <string>
#include <fstream>
#include "list.h"
#include <iostream>

using namespace std;

int main()
{

	ifstream sourcefile;
	ofstream output;


	string filename;

	cout << "imput the name of the file where the temperature data is" << endl << '(';

	cin >> filename;

	sourcefile.open(filename.c_str());
	output.open("output.txt");

	if (!sourcefile)
	{
		cout << "imput failed" << endl;
		return 1;
	}
	
	// TEST CHECKPOINT --- OK

	list names;
	itemtype reader;

	sourcefile >> reader; //primes while loop.

	while(sourcefile && !names.isfull()) // if there is more data and the array is not full....
	{
		if(!names.isthere(reader) && reader < 200) // sends <reader> to the function isthere() which checks if the data is already there. 
			// if it is, it will return the bool value true, and make the if statement false.
			names.insert(reader);
		// if the data represented by reader does not already exist, it will add it to the database.
		sourcefile >> reader;
	}

	cout << "Number of unique readings: " << names.getlength() << endl;

	cout << "here is the list of data" << endl << endl;

	while(names.hasnext())
	{
		reader = names.getnextitem();
		cout << reader << endl;
	}

	names.deleteitem(1337);
	names.resetlist();// deletes 1337 automatically

	return 0;

}

Also, is there any way to use this program on a grouping of strings rather than integers? I tried to switch the typedef statement to

"typedef string itemtype" but it didn't seem to want to do that.

thanks!

[helios]

None of the member functions of list is defined, only declared.

[CQ75]

a new problem

I managed to fix it and get it to work, but I would like to get this thing to work with strings instead.


My book said all I needed to do was to change

typedef int itemtype

to

using namespace std; 

typedef string itemtype

in the .h file, but that didn't seem to do anything, it doesn't seem to reckognize "string" as a valid data type to assign a typedef to.

[firedraco]

Make sure you are including the string header file.

[CQ75]

using namespace std;

and

#include <string>

seem to have no effect on the build errors, in fact using namespace std; makes an additional error.

[helios]

Are you using Visual C++ 6.0?