我正在处理二叉搜索树的模板，但出现以下错误。我知道有类似的帖子，但我无法弄清楚这件事。模板对我来说绝对是一个薄弱的主题，所以我认为我缺少一些基本的语义，但我可以指出它。下面是错误，之后是程序的文件。如果有人能指出我正确的方向，我将不胜感激。
Error 1 error LNK2019: unresolved external symbol "private: bool __thiscall Tree::insertHelper(class TreeNode * &,int)" (?insertHelper@?$Tree@H@@AAE_NAAPAV?$TreeNode@H@@H@Z) referenced in function "public: bool __thiscall Tree::insert(int)" (?insert@?$Tree@H@@QAE_NH@Z) C:\Users\wm\documents\visual studio 2012\Projects\binaryTree\binaryTree\main.obj
-用于测试的基本 main
#include "BinarySearchTree.h"
#include "TreeNode.h"
#include <iostream>
using namespace std;
int main()
{
Tree<int> test;
test.insert(55);
return 0;
}
-树模板
#include <iostream>
#include "TreeNode.h"
using namespace std;
template< class ItemType >
class Tree {
public:
Tree();
~Tree();
bool isEmpty() const;
void makeEmpty();
bool insert( ItemType newItem);
bool retrieve( ItemType searchItem, ItemType & foundItem );
bool deleteItem (ItemType deleteItem);
void print();
private:
TreeNode< ItemType > * rootPtr; // pointer to the root
//utility functions
void printHelper( TreeNode< ItemType > * );
bool insertHelper(TreeNode< ItemType > * & node, ItemType item);
bool deleteHelper( TreeNode< ItemType > * & , ItemType );
void deleteNode( TreeNode<ItemType > * & );
bool retrieveHelper( ItemType, TreeNode< ItemType > * & , ItemType & );
};
template<class ItemType>
Tree<ItemType>::Tree()
{
rootPtr = NULL;
}
template<class ItemType>
Tree<ItemType>::~Tree()
{
makeEmpty();
}
template<class ItemType>
bool Tree<ItemType>::isEmpty() const
//Returns True if the tree is empty, otherwise returns false
//Postcondition: Tree is unchanged.
{
if(rootPtr == NULL)
{
return true;
}
else
{
return false;
}
}
template<class ItemType>
void Tree<ItemType>::makeEmpty()
//Makes the tree empty if it is not empty already.
//Preconditions: The tree exists.
//Postconditions: Tree is now empty. Any dynamically allocated memory which is no longer used is returned to the system.
{
return;
}
template<class ItemType>
bool Tree<ItemType>::insert( ItemType newItem)
// Inserts a copy of newItem in the tree.
//Precondition: The tree exists and has binary search property.
//Postcondition: if the tree already has an item where item == newItem, the function returns false and the trre is unchanged.
//Otherwise, the newItem is inserted in the tree preserving and the binary search property is maintained.
{
if(rootPtr == NULL)
{
rootPtr->data = newItem;
return true;
}
else
{
return insertHelper(rootPtr, newItem);
}
}
template<class ItemType>
bool insertHelper( TreeNode< ItemType > * & node, ItemType item)
{
if( item < node->data)//left
{
if(node->leftPtr == NULL)
{
node->leftPtr = new TreeNode<ItemType>(item);
return true;
}
else
{
return insertHelper(node->leftPtr,item);
}
}
else if(node->data < item)//right
{
if(node->righChild == NULL)
{
node->rightPtr = new TreeNode<ItemType>(item);
return true;
}
else
{
return insertHelper(node->rightPtr,item);
}
}
else// same value
{
return false;
}
}
template<class ItemType>
bool Tree<ItemType>::retrieve( ItemType searchItem, ItemType & foundItem )
// Given a searchItem, it tries to retrieve as foundItem, an item in the tree where the item == searchItem.
// Precondition:The tree exists and has the binary search property.
// Postcondition: If the tree already has an item where item == searchItem, foundItem is set to that item, and the function returns true.
// If the tree has no such item, the function returns false and foundItem remains unchanged. The tree is unchanged.
{
}
template<class ItemType>
bool Tree<ItemType>::deleteItem (ItemType deleteItem)
// Given a deleteItem, it deltes from the tree any item where item == deleteItem.
// Precondition: Tree exists and has binary search property.
// Postcondition: If the tree has an item where item == deleteItem, that item is removed from the tree, and the function returns true, and
// the binary search property is maintained. If the tree has no such item, the function returns false and the tree remains unchanged.
{
}
template<class ItemType>
void Tree<ItemType>::print()
// Prints the items in the tree in ascending order to the screen
// Precondition: The tree exists and has binary search property.
// Postcondition: The items have been printed in ascending order and the tree is unchanged
{
}
template<class ItemType>
void printHelper( TreeNode< ItemType > * )
{
}
template<class ItemType>
bool deleteHelper( TreeNode< ItemType > * & , ItemType )
{
}
template<class ItemType>
void deleteNode( TreeNode<ItemType > * & )
{
}
template<class ItemType>
bool retrieveHelper( ItemType, TreeNode< ItemType > * & , ItemType & )
{
}
-树节点
#ifndef TREENODE_H
#define TREENODE_H
template< class ItemType > class Tree; // forward declarations
template<class ItemType>
class TreeNode {
friend class Tree< ItemType >; // make Tree a friend
public:
TreeNode( ItemType ); // constructor
TreeNode(); // constructor with data uninitialized
ItemType getData() const; // return data in the node
private:
ItemType data;
TreeNode< ItemType > *leftPtr;
TreeNode< ItemType > *rightPtr;
};
// Constructor
template<class ItemType>
TreeNode< ItemType >::TreeNode( ItemType newItem )
{
data = newItem;
leftPtr = NULL;
rightPtr = NULL;
}
template<class ItemType>
TreeNode< ItemType >::TreeNode( )
{
leftPtr = NULL;
rightPtr = NULL;
}
// Return a copy of the data in the node
template< class ItemType >
ItemType TreeNode< ItemType >::getData() const
{
return data;
}
#endif
最佳答案
呵呵。问题是您忘记了 insertHelper 函数名称前面的作用域限定符 Tree
只需这样做:
template<class ItemType>
bool Tree<ItemType>::insertHelper( TreeNode< ItemType > * & node, ItemType item)
顺便说一下，链接器错误应该会提示您这就是问题所在。首先，你知道你有链接问题，而不是编译问题。其次，您知道无法找到的符号是 *Tree
关于c++ - 模板化二叉搜索树 C++， Unresolved external 错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/16504496/