c++ - 错误 LNK2019：无法解析的外部符号有关缺少什么的帮助？

Question

1>------ Build started: Project: project4, Configuration: Debug Win32 ------
1>  proj4_driver.cpp
1>proj4_driver.obj : error LNK2019: unresolved external symbol "public: class cop4530::BST<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > > const & __thiscall cop4530::BST<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > >::operator=(class cop4530::BST<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > > const &)" (??4?$BST@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@cop4530@@QAEABV01@ABV01@@Z) referenced in function _main
1>proj4_driver.obj : error LNK2019: unresolved external symbol "public: __thiscall cop4530::BST<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > >::BST<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > >(int)" (??0?$BST@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@cop4530@@QAE@H@Z) referenced in function _main
1>proj4_driver.obj : error LNK2019: unresolved external symbol "public: __thiscall cop4530::BST<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > >::BST<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > >(class cop4530::BST<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > > const &)" (??0?$BST@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@cop4530@@QAE@ABV01@@Z) referenced in function _main
1>proj4_driver.obj : error LNK2019: unresolved external symbol "public: __thiscall cop4530::BST<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > >::BST<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > >(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,int)" (??0?$BST@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@cop4530@@QAE@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@H@Z) referenced in function _main
1>proj4_driver.obj : error LNK2019: unresolved external symbol "public: class cop4530::BST<int> const & __thiscall cop4530::BST<int>::operator=(class cop4530::BST<int> const &)" (??4?$BST@H@cop4530@@QAEABV01@ABV01@@Z) referenced in function _main
1>proj4_driver.obj : error LNK2019: unresolved external symbol "public: __thiscall cop4530::BST<int>::BST<int>(int)" (??0?$BST@H@cop4530@@QAE@H@Z) referenced in function _main
1>proj4_driver.obj : error LNK2019: unresolved external symbol "public: __thiscall cop4530::BST<int>::BST<int>(class cop4530::BST<int> const &)" (??0?$BST@H@cop4530@@QAE@ABV01@@Z) referenced in function _main
1>proj4_driver.obj : error LNK2019: unresolved external symbol "public: __thiscall cop4530::BST<int>::BST<int>(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,int)" (??0?$BST@H@cop4530@@QAE@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@H@Z) referenced in function _main
1>c:\users\ah09e\documents\visual studio 2010\Projects\project4\Debug\project4.exe : fatal error LNK1120: 8 unresolved externals
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

这是一个驱动程序：

    #include <iostream>
    #include <string>
    #include "bst.h"

    using namespace std;
    using namespace cop4530;

    int main() {
    string input;

// get a list of integer values
cout << "Enter a list of integer values in one line: ";
getline(cin, input);

// create a binary search tree
BST<int> bst1(input);
if (!bst1.empty()) {
    cout << "Inorder traversal: ";
    bst1.printInOrder();
    cout << "Level order traversal: ";
/////////////bst1.printLevelOrder();

    // test copy constructor
    BST<int> bst2(bst1);
    cout << "Testing copy constructor: ";
    //////////////bst2.printLevelOrder();

    // test assignment operator
    BST<int> bst3;
    bst3 = bst1;
    cout << "Testing assignment operator: ";
    ////////////bst3.printLevelOrder();
 }

// get a list of string values
cout << "Enter a list of string values in one line: ";
getline(cin, input);

// create a binary search tree
BST<string> bsts1(input);
if (!bsts1.empty()) {
    cout << "Inorder traversal: ";
    bsts1.printInOrder();
    cout << "Level order traversal: ";
////////bsts1.printLevelOrder();

    // test copy constructor
    BST<string> bst2(bsts1);
    cout << "Testing copy constructor: ";
    ////////////bst2.printLevelOrder();

    // test assignment operator
    BST<string> bst3;
    bst3 = bsts1;
    cout << "Testing assignment operator: ";
    ///////////bst3.printLevelOrder();
 }

cout << "Enter a list of integer values: ";
getline(cin, input);
/////bst1.buildFromInputString(input);
cout << "Level order traversal: ";
////bst1.printLevelOrder();

cout << "\n===================\n";
cout << "Operation Manual:" << endl;
cout << "d: delete value;\ti: insert value;" << endl;
cout << "h: height of tree; \tn: number of nodes" << endl;
cout << "o: in order print; \tl: level order print" << endl;
cout << "s: search value;\tq: quit" << endl;
cout << "===================\n";
cout << "choice: ";
int tmp;
while (getline(cin, input)) {
if (input == "q")
    break;
if (input == "d") {
    cout << "Type value to delete: ";
    cin >> tmp;
    cin.ignore();
    bst1.remove(tmp);
} else if (input == "i") {
    cout << "Type value to insert: ";
    cin >> tmp;
    cin.ignore();
    bst1.insert(tmp);
} else if (input == "o") {
    cout << "In order traversal: ";
    bst1.printInOrder();
} else if (input == "l") {
    cout << "Level order traversal: ";
    ///////bst1.printLevelOrder();
} else if (input == "h") {
    cout << "Height: ";
    cout << bst1.height() << endl;
} else if (input == "n") {
    cout << "Number of nodes: ";
    cout << bst1.numOfNodes() << endl;
} else if (input == "s") {
    cout << "Type value to search: ";
    cin >> tmp;
    cin.ignore();
    if (bst1.contains(tmp)) {
    cout << "contains " << tmp << endl;
    } else {
    cout << "does not contains " << tmp << endl;
    }
}

cout << "\n===================\n";
cout << "Operation Manual:" << endl;
cout << "d: delete value;\ti: insert value;" << endl;
cout << "h: height of tree; \tn: number of nodes" << endl;
cout << "o: in order print; \tl: level order print" << endl;
cout << "s: search value;\tq: quit" << endl;
cout << "===================\n";
cout << "choice: ";
}
return 0;
}

和 bst.h：

#ifndef COP4530_PROJ4_H
#define COP4530_PROJ4_H

#include<iostream>
#include<string>
using std::string;

namespace cop4530{

//using std::string;
int default_threshold_value = 1;

template <typename T>
class BST
{

public:

BST(int th=default_threshold_value); 
BST(const string input, int th=default_threshold_value);
BST(const BST&);
~BST();//
void buildFromInputString(const string input);
const BST & operator=(const BST & rhs);//
bool empty();//


void printInOrder() const;//
//void printLevelOrder() const;//
int numOfNodes() const;//
int height() const;//
void makeEmpty();//
void insert(const T& v);//
void remove(const T& v);//
bool contains (const T& v);//


private:
struct BSTNode
{
T element;
BSTNode *left;
BSTNode *right;
int height;
//void printInOrder(BSTNode *t) const;

BSTNode(const T & theElement, BSTNode *lt, BSTNode *rt, int h=0)
    : element(theElement), left(lt), right(rt), height(h) {}
};

BSTNode *root;

void printInOrder(BSTNode *t) const;//
//void printLevelOrder(BSTNode *t) const;
void makeEmpty(BSTNode* &t);//
void insert(const T& v, BSTNode *&t);//
void remove(const T& v, BSTNode *&t);//
bool contains(const T& v, BSTNode *&t);//
int numOfNodes(BSTNode *t) const;//
int height(BSTNode *t) const;//
BSTNode * clone(BSTNode *t) const;//

};
#include "bst1.hpp"
}
#endif

这是 bst1.hpp

template <typename T>
void BST<T>::buildFromInputString(const string input)
{
    //////////makeEmpty();
    cin >> input;

}

template <typename T>
BST<T>::~BST()
{
    makeEmpty();
}

/*template <typename T>
const BST<T>::BST & operator=(const BST & rhs)
{
    if (this != &rhs)
    {
        makeEmpty();
        root = clone( rhs.root)
    }
    return *this;
}*/

template <typename T>
bool BST<T>::empty()
{
//if (contains(root)==(-1)) 
if ( 1==1)  
    return true;
else
    return false;
}

template <typename T>
void BST<T>::printInOrder() const
{
    printInOrder(root);
}

/*template <typename T>
void BST<T>::printLevelOrder() const
{
    printLevelOrder(root);
}*/

template <typename T>
int BST<T>::numOfNodes() const
{
    return numOfNodes(root);
}
template <typename T>
int BST<T>::height() const
{
    return height(root);
}

template <typename T>
void BST<T>::makeEmpty()
{
    makeEmpty(root);
}

template <typename T>
void BST<T>::insert(const T& v)
{
    insert(v, root);
}

template <typename T>
void BST<T>::remove(const T& v)
{
    remove(v, root);
}

template <typename T>
bool BST<T>::contains(const T& v)
{
    return contains(v, root);
}

template <typename T>
bool BST<T>::contains(const T& v, BSTNode *&t)
{
    if( t == NULL)
        return false;
    else if(v < t->element)
        return contains(v, t->left);
    else if(t->element < v)
        return contains(v, t->right);
    else
        return true;
}

template <typename T>
int BST<T>::numOfNodes(BSTNode *t) const
{
    int nodes = 0;
    if (t!=NULL)
    {
        nodes++;
        numOfNodes(t->left);
        numOfNodes(t->right);
    }
    return nodes;
}

template <typename T>
void BST<T>::printInOrder(BSTNode *t) const
{

if (left != 0)
printInOrder(t->left);
cout << t << endl;
if (right != 0)
printInOrder(t->right);

}


//void BST<T>::printLevelOrder(BSTNode *t) const


template <typename T>
void BST<T>::makeEmpty(BSTNode * & t)
{
    if(t != NULL)
    {
        makeEmpty(t->left);
        makeEmpty(t->right);
        delete t;
    }
    t = NULL;
}

template <typename T>
void BST<T>::insert(const T& v, BSTNode *&t)
{
    if(t = NULL)
        t = new BSTNode(v, NULL, NULL);
    else if(v < t->element)
        insert(v,t->left);
    else if(t->element < v)
        insert(v,t->right);
    else
        ;
}

template <typename T>
void BST<T>::remove(const T& v, BSTNode *&t)
{
    if(t == NULL)
        return;
    if(v < t->element)
        remove(v, t->left);
    else if (t->element < v)
        remove(v,t->right);
    else
    {
        BSTNode *oldNode = t;
        t = (t->left != NULL) ? t->left : t->right;
        delete oldNode;
    }

}
//else if (t->left != NULL && t->right != NULL)



template <typename T>
int BST<T>::height(BSTNode *t) const
{
    return t == NULL ? -1: t->height;
}

template <class T>
typename BST<T>::BSTNode * BST<T>::clone(BSTNode *t) const
{
    if(t==NULL)
        return NULL;

    return new BSTNode( t->element, clone(t->left), clone(t->right));

}

我遇到了链接器问题。在网站上找不到任何可以专门解决我的问题的代码。一直在研究二叉搜索树，但几乎没有解决这个特定方面的结果。就我而言，所有库和文件都添加在各自的区域中，将非常感谢一些帮助。

score 0 · Accepted Answer

You must not separate interface and implementation for templates. Define your methods in you .h-file, otherwise the compiler can't create your concrete types.

score 0 · Accepted Answer

如果您真的想将模板实现和声明分开。您应该将行尾更改bst.h为

#include "bst1.hpp"

至

#include "bst1.cpp"

并且bst1.hpp应该重命名为bst1.cpp（你bst1.hpp真的包含你需要的所有实现），因此，编译器可以通过知道里面的定义来实例化你的模板bst1.cpp。

score 0 · Accepted Answer

getline(cin, input);

在驱动程序中没有任何意义，与 cout 类似，在驱动程序中也没有任何意义。

对于驱动程序编程，您需要从小处着手，逐步推进。

从小处着手，从调试（并使用程序读取调试消息）开始。

您可以在此处找到入门教程。

有关更多信息，我建议您查看 Microsoft 的驱动程序 sdk，这很有帮助。

c++ - 错误 LNK2019：无法解析的外部符号 有关缺少什么的帮助？

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c++ - 错误 LNK2019：无法解析的外部符号有关缺少什么的帮助？