unresolved external symbol errors

This is a discussion on unresolved external symbol errors within the C++ Programming forums, part of the General Programming Boards category; I know im not doing something right but i cant figure out atm. Ive tried looking up the error at ...

  1. #1
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    unresolved external symbol errors

    I know im not doing something right but i cant figure out atm. Ive tried looking up the error at microsofts page and i cant really make much sense of it. I have a client program that has:
    Code:
    #include "bintree.h"
    #include <iostream>
    #include <stdlib.h>
    using namespace std;
    
    struct datanode
    {
    	int key;
    	float gpa;
    };
    
    int menu();
    void holdscreen();
    
    int main()
    {
    	Binary_tree<datanode> tree;
    	datanode data;
    	Binary_node<datanode> * pointer;
    	int choice, key;
    	float gpa;
    	do
    	{
    		system("cls");
    		choice = menu();
    		switch(choice)
    		{
    			case 1: tree.fill_tree(); break;
    			case 2: {
    						cout << "Enter key and gpa:";
    						cin >> key >> gpa;
    						data.key = key;
    						data.gpa = gpa;
    						tree.insert(data);
    					} break;
    			case 3: tree.inorder(); holdscreen(); break;
    			case 4: tree.preorder(); holdscreen(); break;
    			case 5: tree.postorder(); holdscreen(); break;
    			case 6: tree.descending(); holdscreen(); break;
    			case 7: { cout << "Size = " << tree.size() << endl; holdscreen(); } break;
    			case 8: { cout << "Average = " << tree.average() << endl; holdscreen(); } break;
    			case 9: { cout << "Enter key to search for:"; 
    					  cin >> key;
    					  tree.search(key, pointer);
    					  if (pointer == NULL) cout<<"NOT FOUND\n"; 
    					  else 
    						  cout << "key = " << pointer->data.key << " gpa = " << pointer->data.gpa << endl;
    					  holdscreen(); 
    					} break;
    			case 10: {cout << "Enter key of node to delete:";
    					  cin >> key;
    					  if (!tree.remove(key)) cout << "NOT FOUND\n"; holdscreen();
    					 }break;
    			case 11: break;
    			default: {cout << "Invalid choice\n"; holdscreen();}
    		}
    	}while (choice != 11);
    	return 0;
    }
    
    int menu()
    {
    	int choice = 0;
    	cout << "1. Fill tree from file LAB5.in" << endl;
    	cout << "2. Insert a node into the tree" << endl;
    	cout << "3. Print Keys only in ascending order" << endl;
    	cout << "4. Print Keys with GPSs in preorder" << endl;
    	cout << "5. Print Keys with GPSs in postorder" << endl;
    	cout << "6. Print Keys with GPSs in descending order" << endl;
    	cout << "7. Count nodes in tree" << endl;
    	cout << "8. Calculate average of GPAs in tree" << endl;
    	cout << "9. Search for a Key in the tree" << endl;
    	cout << "10. Delete a node from the tree" << endl;
    	cout << "11. Quit" << endl;
    	cin >> choice;
    	return choice;
    }
    
    void holdscreen()
    {
    	cin.ignore();
    	cin.ignore();
    }
    and when i try to compile it all i get is this:
    Code:
    Linking...
    : error LNK2001: unresolved external symbol "public: bool __thiscall Binary_tree<struct datanode>::remove(int)" (?remove@?$Binary_tree@Udatanode@@@@QAE_NH@Z)
    : error LNK2001: unresolved external symbol "public: void __thiscall Binary_tree<struct datanode>::search(int,struct Binary_node<struct datanode> * &)" (?search@?$Binary_tree@Udatanode@@@@QAEXHAAPAU?$Binary_node@Udatanode@@@@@Z)
    : error LNK2001: unresolved external symbol "public: float __thiscall Binary_tree<struct datanode>::average(void)const " (?average@?$Binary_tree@Udatanode@@@@QBEMXZ)
     : error LNK2001: unresolved external symbol "public: int __thiscall Binary_tree<struct datanode>::size(void)const " (?size@?$Binary_tree@Udatanode@@@@QBEHXZ)
     : error LNK2001: unresolved external symbol "public: void __thiscall Binary_tree<struct datanode>::descending(void)const " (?descending@?$Binary_tree@Udatanode@@@@QBEXXZ)
    : error LNK2001: unresolved external symbol "public: void __thiscall Binary_tree<struct datanode>::postorder(void)const " (?postorder@?$Binary_tree@Udatanode@@@@QBEXXZ)
    : error LNK2001: unresolved external symbol "public: void __thiscall Binary_tree<struct datanode>::preorder(void)const " (?preorder@?$Binary_tree@Udatanode@@@@QBEXXZ)
    : error LNK2001: unresolved external symbol "public: void __thiscall Binary_tree<struct datanode>::inorder(void)const " (?inorder@?$Binary_tree@Udatanode@@@@QBEXXZ)
     : error LNK2001: unresolved external symbol "public: void __thiscall Binary_tree<struct datanode>::insert(struct datanode const &)" (?insert@?$Binary_tree@Udatanode@@@@QAEXABUdatanode@@@Z)
    lab5.obj : error LNK2001: unresolved external symbol "public: void __thiscall Binary_tree<struct datanode>::fill_tree(void)" (?fill_tree@?$Binary_tree@Udatanode@@@@QAEXXZ)
    : error LNK2001: unresolved external symbol "public: __thiscall Binary_tree<struct datanode>::Binary_tree<struct datanode>(void)" (??0?$Binary_tree@Udatanode@@@@QAE@XZ)
    Debug/btree.exe : fatal error LNK1120: 11 unresolved externals
    Error executing link.exe.
    
    lab5.exe - 12 error(s), 0 warning(s)
    bintree.h
    Code:
    #ifndef BINARY_TREE_H
    #define BINARY_TREE_H
    
    template <class Entry>
    struct Binary_node
    {
    	Entry data;
    	Binary_node<Entry> *left;
    	Binary_node<Entry> *right;
    	Binary_node();
    	Binary_node(const Entry &x);
    };
    
    template <class Entry>
    class Binary_tree
    {
    public:
    	Binary_tree();
    	void insert(const Entry &);
    	void fill_tree();
    	void inorder() const;
    	void preorder() const;
    	void descending() const;
    	void postorder() const;
    	int size() const;
    	float average() const;
    	void search (int target_key, Binary_node<Entry> * & target_pointer);
    	bool remove(int target);
    private:
    	Binary_node<Entry> * root;
    	recursive_insert(Binary_node<Entry>* &, const Entry &);
    	//more to come
    };
    #endif
    bintree.cpp
    Code:
    #include "bintree.h"
    #include <fstream>
    #include <assert.h>
    #include <iostream>
    using namespace std;
    
    template <class Entry>
    Binary_node<Entry>::Binary_node()
    {
    	left = right = NULL;
    }
    
    template <class Entry>
    void Binary_tree<Entry>::insert(const Entry & data)
    {
    	recursive_insert(root, data);
    }
    
    template <class Entry>
    void Binary_node<Entry>::recursive_insert(Binary_node<Entry>* & sub_root, const Entry & data)
    {
    	if(sub_root == NULL) sub_root = new Binary_node<Entry> (data);
    	else if (data.key < sub_root->data.key)recursive_insert(sub_root->left, data);
    		 else recursive_insert(sub_root->right, data);
    }
    
    template <class Entry>
    void Binary_tree<Entry>::fill_tree()
    {
    	datanode data;
    	ifstream infile("C:LAB5.in");
    	assert( !infile.fail() );
    	while( !infile.eof() )
    	{
    		infile >> data.key >> data.gpa;
    		insert(data);
    	}	
    }
    
    template <class Entry>
    void Binary_tree<Entry>::descending() const
    {cout<<"in descending";}
    
    template <class Entry>
    int Binary_tree<Entry>::size() const
    {cout<<"in size";}
    
    template <class Entry>
    float Binary_tree<Entry>::average() const
    {cout<<"in avg";}
    
    template <class Entry>
    void Binary_tree<Entry>::search (int target_key, Binary_node<Entry> * & target_pointer)
    {
    /*	
    	in progress
    */
    }
    
    template <class Entry>
    bool Binary_tree<Entry>::remove(int target)
    {cout<<"in remove";}
    
    template <class Entry>
    void Binary_tree<Entry>::inorder(Binary_node<Entry> *root) const
    {
    	if( root == NULL ) return;
    	inorder(root->left);
    	cout << root->key << endl;
    	inorder(root->right);
    }
    
    template <class Entry>
    void Binary_tree<Entry>::preorder(Binary_node<Entry> *root) const
    {
    	if( root == NULL ) return;
    	cout << root->key << " " << root->gpa << endl;
    	preorder(root->left);
    	preorder(root->right);
    }
    
    template <class Entry>
    void Binary_tree<Entry>::postorder(Binary_node<Entry> *root) const
    {
    	if( root == NULL ) return;
    	postorder(root->left);
    	postorder(root->right);
    	cout << root->key << " " << root->gpa << endl;
    }
    thnxs in advance
    Last edited by I BLcK I; 05-16-2007 at 06:44 PM.

  2. #2
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    Template code cannot be put in a .cpp file. Move all that code to bintree.h.

  3. #3
    Frequently Quite Prolix dwks's Avatar
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    Canada
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    assert.h is generally cassert in C++ (with no .h), though it's okay how you have it. The same for stdlib.h.

    Also, read this FAQ to see why this is a bad idea: http://faq.cprogramming.com/cgi-bin/...&id=1043284351
    Code:
    	while( !infile.eof() )
    	{
    		infile >> data.key >> data.gpa;
    		insert(data);
    	}
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
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