带有unique_ptr的通用单链表，MS visual studio C++中存在未知错误

Question

我在这里做了一个扩展。我知道我对何时使用unique_ptr和何时不使用有了更好的理解。尽管如此，强调这一点，我仍然会遇到一些错误，很可能是因为我对unique_pr的理解不够好。

以下是我得到的错误：

1>------ Build started: Project: LinkedList, Configuration: Debug Win32 ------
1>main.cpp
1>c:devlinkedlistlinkedlistsinglelinkedlist.h(166): error C2679: binary '=': no operator found which takes a right-hand operand of type 'SingleLinkedList<int>::Node *' (or there is no acceptable conversion)
1>c:program files (x86)microsoft visual studio2017communityvctoolsmsvc14.14.26428includememory(2309): note: could be 'std::unique_ptr<SingleLinkedList<int>::Node,std::default_delete<_Ty>> &std::unique_ptr<_Ty,std::default_delete<_Ty>>::operator =(const std::unique_ptr<_Ty,std::default_delete<_Ty>> &)'
1>        with
1>        [
1>            _Ty=SingleLinkedList<int>::Node
1>        ]
1>c:program files (x86)microsoft visual studio2017communityvctoolsmsvc14.14.26428includememory(2247): note: or       'std::unique_ptr<SingleLinkedList<int>::Node,std::default_delete<_Ty>> &std::unique_ptr<_Ty,std::default_delete<_Ty>>::operator =(std::unique_ptr<_Ty,std::default_delete<_Ty>> &&) noexcept'
1>        with
1>        [
1>            _Ty=SingleLinkedList<int>::Node
1>        ]
1>c:program files (x86)microsoft visual studio2017communityvctoolsmsvc14.14.26428includememory(2173): note: or       'std::unique_ptr<SingleLinkedList<int>::Node,std::default_delete<_Ty>> &std::unique_ptr<_Ty,std::default_delete<_Ty>>::operator =(std::nullptr_t) noexcept'
1>        with
1>        [
1>            _Ty=SingleLinkedList<int>::Node
1>        ]
1>c:devlinkedlistlinkedlistsinglelinkedlist.h(166): note: while trying to match the argument list '(std::unique_ptr<SingleLinkedList<int>::Node,std::default_delete<_Ty>>, SingleLinkedList<int>::Node *)'
1>        with
1>        [
1>            _Ty=SingleLinkedList<int>::Node
1>        ]
1>c:devlinkedlistlinkedlistsinglelinkedlist.h(163): note: while compiling class template member function 'void SingleLinkedList<int>::deleteHead(void)'
1>c:devlinkedlistlinkedlistsinglelinkedlist.h(85): note: see reference to function template instantiation 'void SingleLinkedList<int>::deleteHead(void)' being compiled
1>c:devlinkedlistlinkedlistsinglelinkedlist.h(83): note: while compiling class template member function 'SingleLinkedList<int>::~SingleLinkedList(void)'
1>cI made a post that will be an extention to this [enter link description here][1]:devlinkedlistlinkedlistmain.cpp(23): note: see reference to function template instantiation 'SingleLinkedList<int>::~SingleLinkedList(void)' being compiled
1>c:devlinkedlistlinkedlistmain.cpp(23): note: see reference to class template instantiation 'SingleLinkedList<int>' being compiled
1>Done building project "LinkedList.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

我应该再次提到，我是MS visual studio C++和unique_ptr的新手。我最初只使用新指针编写这个实现，但有人建议我使用unique_ptr重写它。

这是我的头文件：

#ifndef SingleLinkedList_h
#define SingleLinkedList_h
#include <iostream>
template <class T>
class SingleLinkedList {
private:
struct Node {
T data;
std::unique_ptr<Node> next = nullptr;
Node(T x) : data(x), next(nullptr) {}
};
std::unique_ptr<Node> head = nullptr;
std::unique_ptr<Node> tail = nullptr;
// This function is for the overloaded operator << 
void display(std::ostream &str) const {
for (Node* loop = head.get(); loop != nullptr; loop = loop->next.get()) {
str << loop->data << "t";
}
str << "n";
}
public:
// Constructors
SingleLinkedList() = default;                                           // empty constructor 
SingleLinkedList(SingleLinkedList const &source);                       // copy constructor
// Rule of 5
SingleLinkedList(SingleLinkedList &&move) noexcept;                     // move constructor
SingleLinkedList& operator=(SingleLinkedList &&move) noexcept;          // move assignment operator
~SingleLinkedList();                                    
// Overload operators
SingleLinkedList& operator=(SingleLinkedList const &rhs);
friend std::ostream& operator<<(std::ostream &str, SingleLinkedList &data) {
data.display(str);
return str;
}
// Memeber functions
void swap(SingleLinkedList &other) noexcept;
bool empty() const { return head.get() == nullptr; }
void push(const T &theData);                            
void push(T &&theData);
void display() const;
void insertHead(const T &theData);
void insertTail(const T &theData);
void insertPosition(int pos, const T &theData);
void deleteHead();
void deleteTail();
void deletePosition(int pos);
bool search(const T &x);
};
template <class T>
SingleLinkedList<T>::SingleLinkedList(SingleLinkedList<T> const &source) {
for(Node* loop = source->head.get(); loop != nullptr; loop = loop->next.get()) {
push(loop->data);
}
}
template <class T>
SingleLinkedList<T>::SingleLinkedList(SingleLinkedList<T>&& move) noexcept {
move.swap(*this);
}
template <class T>
SingleLinkedList<T>& SingleLinkedList<T>::operator=(SingleLinkedList<T> &&move) noexcept {
move.swap(*this);
return *this;
}
template <class T>
SingleLinkedList<T>::~SingleLinkedList() {
while (head != nullptr) {
deleteHead();
}
}
template <class T>
SingleLinkedList<T>& SingleLinkedList<T>::operator=(SingleLinkedList const &rhs) {
SingleLinkedList copy{ rhs };
swap(copy);
return *this;
}
template <class T>
void SingleLinkedList<T>::swap(SingleLinkedList &other) noexcept {
using std::swap;
swap(head, other.head);
swap(tail, other.tail);
}
template <class T>
void SingleLinkedList<T>::push(const T &theData) {
std::unique_ptr<Node> newNode = std::make_unique<Node>(theData);
if (head == nullptr) {
head = std::move(newNode);
tail = head.get();
}
else {
tail->next = std::move(newNode);
tail = tail->next.get();
}
}
//template <class T>
//void SingleLinkedList<T>::push(T &&theData) {
//  std::unique_ptr<Node> newNode = std::make_unique<Node>(std::move(theData));
//
//  if (head == nullptr) {
//      head = std::move(newNode);
//      tail = head.get();
//  }
//
//  else {
//      tail->next = std::move(newNode);
//      tail = tail->next.get();
//  }
//}

template <class T>
void SingleLinkedList<T>::display() const {
Node* newNode = head.get();
while (newNode != nullptr) {
std::cout << newNode->data << "t";
newNode = newNode->next;
}
}
template <class T>
void SingleLinkedList<T>::insertHead(const T &theData) {
std::unique_ptr<Node> newNode = std::make_unique<Node>(theData);
newNode->next = head.get();
head = newNode;
}
template <class T>
void SingleLinkedList<T>::insertTail(const T &theData) {
std::unique_ptr<Node> newNode = std::make_unique<Node>(theData);
tail->next = newNode;
tail = newNode;
}
template <class T>
void SingleLinkedList<T>::insertPosition(int pos, const T &theData) {
}
template <class T>
void SingleLinkedList<T>::deleteHead() {
Node* old = head.get();
delete old;
head = head->next.get();
}
template <class T>
void SingleLinkedList<T>::deleteTail() {
}
template <class T>
void SingleLinkedList<T>::deletePosition(int pos) {
}
template <class T>
bool SingleLinkedList<T>::search(const T &x) {
}


#endif /* SingleLinkedList_h*/

这是主.cpp文件：

#include <algorithm>
#include <cassert>
#include <iostream>
#include <ostream>
#include <iosfwd>
#include "SingleLinkedList.h"

int main(int argc, const char * argv[]) {

///////////////////////////////////////////////////////////////////////
///////////////////////////// Single Linked List //////////////////////
///////////////////////////////////////////////////////////////////////
SingleLinkedList<int> obj;
obj.push(2);
obj.push(4);
obj.push(6);
obj.push(8);
obj.push(10);
std::cout<<"n--------------------------------------------------n";
std::cout<<"---------------displaying all nodes---------------";
std::cout<<"n--------------------------------------------------n";
std::cout << obj << std::endl;
//
//    std::cout<<"n--------------------------------------------------n";
//    std::cout<<"-----------------Inserting At End-----------------";
//    std::cout<<"n--------------------------------------------------n";
//    obj.insertTail(20);
//    std::cout << obj << std::endl;
//
//    std::cout<<"n--------------------------------------------------n";
//    std::cout<<"----------------Inserting At Start----------------";
//    std::cout<<"n--------------------------------------------------n";
//    obj.insertHead(50);
//    std::cout << obj << std::endl;
//
//    std::cout<<"n--------------------------------------------------n";
//    std::cout<<"-------------Inserting At Particular--------------";
//    std::cout<<"n--------------------------------------------------n";
//    obj.insertPosition(5,60);
//    std::cout << obj << std::endl;
//
//    std::cout<<"n--------------------------------------------------n";
//    std::cout<<"----------------Deleting At Start-----------------";
//    std::cout<<"n--------------------------------------------------n";
//    obj.deleteHead();
//    std::cout << obj << std::endl;
//
//    std::cout<<"n--------------------------------------------------n";
//    std::cout<<"----------------Deleting At End-----------------";
//    std::cout<<"n--------------------------------------------------n";
//    obj.deleteTail();
//    std::cout << obj << std::endl;
//
//
//    std::cout<<"n--------------------------------------------------n";
//    std::cout<<"--------------Deleting At Particular--------------";
//    std::cout<<"n--------------------------------------------------n";
//    obj.deletePosition(4);
//    std::cout << obj << std::endl;
//    std::cout << std::endl;
//
//    obj.search(8) ? printf("Yes"):printf("No");



std::cin.get();
}

Answer 1

为链表使用唯一指针是没有意义的。出于锻炼目的，您可以使用原始指针。出于实际目的，请使用std::list或其他容器。

它没有意义的原因是，你的尾巴可能指向同一个节点，而不是另一个节点的下一个节点。那么它就不是独一无二的了。