Question

我在这个网站上看到过这个问题很多，但尝试这里提供的解决方案还没有与我的程序一起使用。所以，我为无数次问这个问题而道歉，但没有什么对我有用。

我编译以下

g++ deque.cpp deque.h driver.cpp

然后得到错误

/tmp/ccvkttRj.o: In function `main':
driver.cpp:(.text+0x20): undefined reference to `Deque<int>::Deque()'
driver.cpp:(.text+0x42): undefined reference to `Deque<int>::addBack(int const&)'
driver.cpp:(.text+0x6f): undefined reference to `Deque<int>::addFront(int const&)'
driver.cpp:(.text+0x8d): undefined reference to `Deque<int>::Deque(Deque<int> const&)'
driver.cpp:(.text+0xa7): undefined reference to `Deque<int>::addBack(int const&)'
driver.cpp:(.text+0xcf): undefined reference to `Deque<int>::isEmpty() const'
driver.cpp:(.text+0xe2): undefined reference to `Deque<int>::removeFront()'
driver.cpp:(.text+0x125): undefined reference to `Deque<int>::isEmpty() const'
driver.cpp:(.text+0x138): undefined reference to `Deque<int>::removeBack()'
driver.cpp:(.text+0x15f): undefined reference to `Deque<int>::~Deque()'
driver.cpp:(.text+0x16b): undefined reference to `Deque<int>::~Deque()'
driver.cpp:(.text+0x190): undefined reference to `Deque<int>::~Deque()'
driver.cpp:(.text+0x1a1): undefined reference to `Deque<int>::~Deque()'
collect2: error: ld returned 1 exit status

据我所知，我在适当的地方使用#include和#ifndef，我的方法签名在我的所有文件中都是一样的。但我必须是错的，否则我不会得到这个错误。

这是我的deque程序：

标题

#ifndef DEQUE_H
#define DEQUE_H
#include <iostream>
using namespace std;

template <class Object>
class Deque
{
 public:
  Deque(); // Constructor.
  Deque(const Deque &rhs); // Copy constructor.
  ~Deque(); // Destructor.

  bool isEmpty() const; // Is deque empty.
  int size() const; // Returns # of deque nodes.
  const Object &getFront() const; // Retrieve front node.
  const Object &getBack() const; // Retrieve tail node.

  void clear(); // Clears all nodes from deque.
  void addFront(const Object &obj); // Add a new node to the front.
  void addBack(const Object &obj); // Add a new node to the rear.
  Object removeFront(); // Remove front node.
  Object removeBack(); // Remove rear node.

  const Deque &operator=(const Deque &rhs); // Assignment.

 private:
  struct DequeNode
  {
    Object item;
    DequeNode *next;
    DequeNode *prev;
  };
  DequeNode *front;
  DequeNode *back;
};

#endif

cpp

#include "deque.h"

template <class Object>
Deque<Object>::Deque() // Constructor.
{
  front = back = NULL;
}

template <class Object>
Deque<Object>::Deque(const Deque &rhs) // Copy constructor.
{
  front = back = NULL;
  *this = rhs;
}

template <class Object>
Deque<Object>::~Deque()  // Destructor.
{
  clear();
}

template <class Object>
bool Deque<Object>::isEmpty() const // Check if deque is empty.
{
  return front == NULL;
}

template <class Object>
int Deque<Object>::size() const // Returns # of nodes.
{
  int i = 0;
  for (DequeNode *ptr = front; ptr != NULL; ptr = ptr->next)
    ++i;

  return i;
}

template <class Object>
const Object &Deque<Object>::getFront() const // Retrieve front node.
{
  if (isEmpty())
    throw "empty queue";

  return front->item;
}

template <class Object>
const Object &Deque<Object>::getBack() const // Retrieve rear node.
{
  if (isEmpty())
    throw "empty queue";

  return back->item;
}

template <class Object>
void Deque<Object>::addFront(const Object &obj) // Add a new node to the front.
{
  DequeNode *newPtr = new DequeNode; // Allocate the node in memory.
  newPtr->item = obj; // Insert obj.
  newPtr->next = front; // What once was front will become next.
  newPtr->prev = NULL; // Front node's prev is always NULL.

  if (isEmpty()) // If empty back points to the same as front.
    back = newPtr;
  else
    front->prev = newPtr; // The old front now points the new insert.

  front = newPtr; // Front now points to the new insert.
}

template <class Object>
void Deque<Object>::addBack(const Object &obj) // Add a new node to the back.
{
  DequeNode *newPtr = new DequeNode; // Allocate the node in memory.
  newPtr->item = obj; // Insert obj.
  newPtr->next = NULL; // The last node always points to null.
  newPtr->prev = back; // Inserting back, so point to what once was the last node.

  if (isEmpty()) // If empty front points to the same as back.
    front = newPtr;
  else
    back->next = newPtr; // Old back needs to point to new insert, not NULL.

  back = newPtr; // Back now points to the new insert.
}

template <class Object>
Object Deque<Object>::removeFront() // Remove front node.
{
  Object frontItem = getFront(); // Save what will be removed, so it can be returned.
  DequeNode *toDelete = front; // What will be deleted.

  if (front == back) // Only 1 item in the deque.
    front = back = NULL;
  else
    {
      front = front->next; // Move the next node up.
      front->prev = NULL; // Front node always points to NULL.
    }
  delete toDelete; // Goodbye what once was front;

  return frontItem;
}

template <class Object>
Object Deque<Object>::removeBack() // Remove back/last node.
{
  Object backItem = getBack(); // Save what will be removed, so it can be returned.
  DequeNode *toDelete = back; // What will be deleted.

  if (front == back) // Only 1 item in the deque.
    front = back = NULL;
  else
    {
      back = back->prev; // Move back up the list.
      back->next = NULL; // Last node always points to NULL.
    }
  delete toDelete; // Goodbye what once was back.

  return backItem;
}

template <class Object>
const Deque<Object> &Deque<Object>::operator=(const Deque &rhs) // Assignment op.
{
  if (this != &rhs) // Avoid self assignment.
    {
      clear(); // Not sure why clear, I'll have to come back to this.
      for (DequeNode *ptr = rhs.front; ptr != NULL; ptr = ptr->next)
    addBack(ptr->item);
    }

  return *this;
}

主

#include <iostream>
#include "deque.h"

using namespace std;

int main( ) {
 Deque<int> deque1;
 int item;

 for ( int j = 0; j < 5; j++ )
   deque1.addBack( j );
 for ( int j = 5; j < 10; j++ )
   deque1.addFront( j );

 Deque<int> deque2 = deque1;
 deque2.addBack( 10 );

 cout << "deque1: " << endl;
 while ( !deque1.isEmpty( ) )
   cout << deque1.removeFront( ) << endl;

 cout << "deque2: " << endl;
 while ( !deque2.isEmpty( ) )
   cout << deque2.removeBack( ) << endl;
}

未定义的函数名称引用，C ++

0 个答案: