Question

我试图在CodeBlocks中第二次在Visual Studio 2013中编写我的代码，我在尝试安排二进制搜索树时遇到错误，这是我的代码 BinarySearchTree.h

#pragma once
template <typename T>
class BinarySearchTree{
private:
    struct Node{
        Node *left;
        Node *right;
        T data;
    };
    Node *root;
public:
    BinarySearchTree();
    bool isEmptyTree() const;
    void insertInBinarySearchTree(T& value);
    void removeFromBinarySearchTree(T& value);
    void printBinarySearchTree();
    void inorderBinarySearchTree(Node *p);
};

这是BinarySearchTree：

#include "BinarySearchTree.h"
#include <iostream>
#include <new>
using namespace std;

template <typename T>
BinarySearchTree<T>::BinarySearchTree(){
    root = nullptr;
}

template <typename T>
void BinarySearchTree<T>::insertInBinarySearchTree(T& value){
    Node *t = new Node;
    Node *parent;
    t->data = value;
    t->left = nullptr;
    t->right = nullptr;
    parent = nullptr;
    if (isEmptyTree()) root = t;
    else{
        Node *currentNode;
        currentNode = root;
        while (currentNode){
            parent = currentNode;
            if (t->data, currentNode->data) currentNode = currentNode->right;
            else currentNode = currentNode->left;
        }
        if (t->data < parent->data) parent->left = t;
        else parent->right = t;
    }
}
template <typename T>
void BinarySearchTree<T>::removeFromBinarySearchTree(T& value){
    bool isElementFound = false;
    if (isEmptyTree()){
        cout << "This tree is empty!" << endl;
        return;
    }
    Node *currentNode;
    Node *parent;
    currentNode = parent;
    while (currentNode != nullptr){
        if (currentNode->data == value){
            isElementFound = true;
            break;
        }
        else{
            parent = currentNode;
            if (value > currentNode->data) currentNode = currentNode->right;
            else currentNode = currentNode->left;
        }
    }
    if (!isElementFound()){
        cout << "Data not found in tree!" << endl;
        return;
    }
    if ((currentNode->left == nullptr && currentNode->right != nullptr) || (currentNode->left != nullptr && currentNode->right == nullptr)){
        if (currentNode->left = nullptr && currentNode->right != nullptr){
            if (parent->left == currentNode){
                parent->left = currentNode->right;
                delete currentNode;
            }
            else{
                parent->right = currentNode->right;
                delete currentNode;
            }
        }
        else{
            if (parent->left == currentNode){
                parent->left = currentNode->left;
                delete currentNode;
            }
            else{
                parent->right = currentNode->left;
                delete currentNode;
            }
        }
        return;
    }

    if (currentNode->left == nullptr && current->right == nullptr){
        if (parent->left == currentNode) parent->left == nullptr;
        else parent->right == nullptr;
        delete currentNode;
        return;
    }
    if (currentNode->left == nullptr && currentNode->right == nullptr){
        Node *checker;
        checker = currentNode->right;
        if ((checker->left == nulptr) && (checker->right == nullptr)){
            currentNode = checker;
            delete checker;
            currentNode->right = nullptr;
        }
        else{
            if ((currentNode->right)->left != nullptr){
                Node *leftCurrentNode;
                Node *leftCurrentNodeParent;
                leftCurrentNodeParent = currentNode->right;
                leftCurrentNode = (currentNode->right)->left;
                while (leftCurrentNode->left != nullptr){
                    leftCurrentNode = leftCurrentNodeParent;
                    leftCurrentNode = leftCurrentNode->left;
                }
                currentNode->data = leftCurrentNode->data;
                delete leftCurrentNode;
                leftCurrentNodeParent->left = nullptr;
            }
            else{
                Node *temporaryNode;
                temporaryNode = currentNode->right;
                currentNode->data = temporaryNode->data;
                currentNode->right = temporaryNode->right;
                delete temporaryNode;
            }
        }
        return;
    }
}
template <typename T>
void BinarySearchTree<T>::printBinarySearchTree(){
    inorderBinarySearchTree(root);
}
template <typename T>
void BinarySearchTree<T>::inorderBinarySearchTree(Node *p){
    if (p != nullptr){
        if (p->left) inorderBinarySearchTree(p->left);
        cout << " " << p->data << " ";
        if (p->right) inorderBinarySearchTree(p->right);
    }
    return;
}
template <typename T>
bool BinarySearchTree<T>::isEmptyTree() const{
    return root == nullptr;
}

最后是main.cpp：

#include <iostream>
#include "BinarySearchTree.h"
using namespace std;

int main()
{
    BinarySearchTree<int> BST;
    int ch, tmp, tmp1;
    while (1)
    {
        cout << endl << endl;
        cout << " Binary Search Tree Operations " << endl;
        cout << " ----------------------------- " << endl;
        cout << " 1. Insertion/Creation " << endl;
        cout << " 2. Removal " << endl;
        cout << " 3. Print " << endl;
        cout << " 4. Exit " << endl;
        cout << " Enter your choice : ";
        cin >> ch;
        switch (ch)
        {
        case 1: cout << " Enter Number to be inserted : ";
            cin >> tmp;
            BST.insertInBinarySearchTree(tmp);
            break;
        case 2: cout << " Enter data to be deleted : ";
            cin >> tmp1;
            BST.removeFromBinarySearchTree(tmp1);
            break;
        case 3: cout << endl;
            cout << " Print tree " << endl;
            cout << " -------------------" << endl;
            BST.printBinarySearchTree();
            break;
        case 4:
            return 0;
        }
    }
}

我发现这个错误导致缺少实现，但是我无法在没有实现的情况下找到函数。

Answer 1

您需要在头文件中实现这些功能

＆＃34;目前使用模板的唯一可移植方式是使用内联函数在头文件中实现它们。＆＃34;

https://books.google.co.il/books?id=n9VEG2Gp5pkC&pg=PA10&lpg=PA10&dq=%22The+only+portable+way+of+using+templates+at+the+moment+is+to+implement+them+in+header+files+by+using+inline+functions.%22&source=bl&ots=Ref8pl8dPX&sig=t4K5gvxtBblpcujNxodpwMfei8I&hl=en&ei=qkR6TvbiGojE0AHq4IzqAg&sa=X&oi=book_result&ct=result#v=onepage&q=%22The%20only%20portable%20way%20of%20using%20templates%20at%20the%20moment%20is%20to%20implement%20them%20in%20header%20files%20by%20using%20inline%20functions.%22&f=false

Answer 2

您遇到的问题是在main.cpp中，您使用int作为模板实例化了您的类，因此在头文件中，所有内容都被视为int。例如。 void insertInBinarySearchTree( int& value );

但是，在实现文件中，仍然使用更通用的模板定义来定义函数，并且在编译时main.cpp将要查找

的函数定义

void insertInBinarySearchTree( int& value );

它失败的原因是因为在cpp文件中你只有

void insertInBinarySearchTree( T& value );。

为了解决这个问题，只需转到cpp的最后一行并添加以下内容：

template class BinarySearchTree<int>;

问题将得到修复，因为已经添加了一个处理整数的定义。

P.S：查看代码，看起来=和==的使用不正确。请记住，=用于分配，==用于检查两个值是否相同。还有许多其他错误，因此我修复了我注意到的here。

LNK2019：未解析的外部符号public

2 个答案: