takeaway.o: In function `takeaway':
project:145: undefined reference to `vtable for takeaway'
project:145: undefined reference to `vtable for takeaway'
takeaway.o: In function `~takeaway':
project:151: undefined reference to `vtable for takeaway'
project:151: undefined reference to `vtable for takeaway'
takeaway.o: In function `gameCore':
project.h:109: undefined reference to `gameCore<int>::initialData(int)'
collect2: ld returned 1 exit status
make: *** [takeaway] Error 1

我不断从链接器收到此错误，我知道它与临时存储 vtable 的内联函数有关。但这意味着什么我不太确定。我认为这与我如何在 takeaway.cpp 的初始化列表中调用 gameCore 的构造函数有关

我有一个模板类 (gameCore.h) 和一个继承自gameCore的类(takeaway.cpp) vtable 错误被调用 3 次 1)在外卖构造函数中 2) 外卖析构函数 3)在gameCores构造函数中

我正在使用 G++ 这是代码: (我知道它可能看起来很难阅读，但我已经明确地标出了错误发生的位置) 外卖.h

#ifndef _TAKEAWAY_H_
#define _TAKEAWAY_H_
#include<map>
#include<cctype>
#include<stack>
#include<map>
#include<iostream>
#include<string>
#include<cstdlib>
#include"gameCore.h"
#include<vector>
using namespace std;
class takeaway : public gameCore<int>
{
 private:

 public:
// template<class Penny>
 void  textualGame();
 bool isNum(string str);
// template<class Penny>
 stack<int> initialData(int initial);
// template<class Position>
 int score (int position);
// template<class Position>
 stack<int> addStack(int currentPos, stack<int> possiblePositions);
// template<class Penny>
 takeaway (int initial);
// template<class Position>
 ~takeaway();
};
bool isNum(string str);
int charToint(char *theChar);
#endif

takeaway.cpp

/*
Description :
    This game communicates with the gameCore class to determine the results
    of a game of takeaway played between two computers or a computer and human.   
*/

#include "takeaway.h"

 /*
 Description:Creates a stack represening initial data
 Note:Change to a vector eventually
 return : stack of int
 */
 stack<int> takeaway:: initialData(int initial){
   stack<int> returnStack;
   int theScore = score(initial);
   int final;
   if(initial ==0)
   {
    final = 1;
   }
   else
   {
    final = 0;
   }
   returnStack.push(theScore);
   returnStack.push(final);
   return returnStack;
 }


 /*
 Description: a textual representation of the game
 Note: This is still terribly wrong
 */

 void textualGame(){
  cout <<"this is the best i could do for a graphical representation";

 }
 /*
 Description: Deetermines if a number is even
 Note: Helper function for determining win or loss positions
 Returns: 1 if it is and 0 if it is not
 */
 int takeaway::score(int position){
  if(position % 2 == 0)
  {
     return 1;
  }
  return 0;
 }
 /*
   Description: Will return a stack , withouth the given postion in it
   will contain all positions possible after the given position
   along with anyother that wehre in the given stack.This function
   Must also update the map to represent updated positions
   Takes: a position to check and a stack to return
   Returns: A stack of possible positions.

 */
 stack<int>  takeaway::addStack(int currentPos, stack<int> possiblePositions ){
  if(currentPos != 0)
  {
    // If even
    if( currentPos % 2 == 0)
    { 
       // Create a data aray with score of the new positon and mark it as not final
    int data[] = {score(currentPos/2),0};
    vector<int> theData(data, data+sizeof(data));
        int pos = currentPos/2;
       // Add it to the map
       //this -> gamesMap[currentPos/2] = dataArray; 
       this -> gamesMap.insert(std::pair<int, vector<int> >(pos, theData));
       // Add it to the possible positions
       possiblePositions.push(pos);
    }
    if(currentPos % 3 == 0)
    {

    int data[] = {score(currentPos/3),0};
       vector<int> theData(data,data+sizeof(data));
       int  pos = currentPos/3;
       //this -> gamesMap[currentPos/3] = dataArray; 
       this -> gamesMap.insert(std::pair<int, vector<int> >(pos, theData));
       possiblePositions.push(pos);
    }
    // Work for the position that represents taking one penny
    int minusFinal = 0;
    if(currentPos - 1 == 0)
    {
      minusFinal = 1;
    }
    int data[] = {score(currentPos - 1),minusFinal};
    vector<int> theData(data,data+sizeof(data));
    int pos  = currentPos - 1;
   // this -> gamesMap[currentPos -1] = dataArary
    this->gamesMap.insert(std::pair<int,vector<int> >(pos, theData));
    possiblePositions.push(pos);
  }
  return possiblePositions;

 }
 /*
 Description: Constructor for the takeaway game
OA takes: a initial position, and initial data for it

 */
 takeaway::takeaway(int initial):gameCore<int>::gameCore(initial){ //<--- ERROR HERE
 //Constructor
 }
 /*
 Description: Destuctor
 */
 takeaway::~takeaway(){ // <--------------------- ERROR HERE
 //Destructor
 }


//checks input and creates game.
int main(int argc, char* argv[]){
  int numberPennies ;
  string game = argv[0];
  if(argc == 2 && isNum(argv[1]) )
  {
    int pennies = charToint(argv[1]);
     takeaway gameInstance(pennies ); // Creates a instance of $
  }
 //  else if(argc == 3 && argv[1] == "play" && isNum(argv[2]) )
 // {
 //   int pennies = charToint(argv[2]);
 //   takeaway<int> gameInstance(pennies); // Craete a human playab$
 // }
  else
  {
    cerr << "Error->Usage: " << game <<" [play] numberOfPennies \n";
    exit (1);
  }
 return 0;
 }

//Converts a char to a integer
int charToint(char *theChar){
  int theInt = atoi(theChar);
  return theInt;
}
 //Determines if a string is numeric
bool isNum(string str){ 
  for(int i = 0;i < str.length() ;i++){
   if(isdigit(str[i]) != 1)
   {
     cerr << "Error->Input: Number must be a Positive Integer the charecter '" << str[i]<< "' invalidated your input. \n" ;
     exit(1);
     return false;
   }
  }
  return true;
}

gameCore.h

/*
gameCore.h

Description:
    This class created gameMap that are written as a template
    They will communicate with the specific game and the algorithm
    To keep track of positions ans there values.
*/
#ifndef GAMECORE_H
#define GAMECORE_H
#include <map>
#include <stack>
#include <string>
#include <vector>
using namespace std;


template <class Position>
class gameCore
{
 protected:
    //Best Move used by algorithim
    Position bestMove;
    //The current highest score used by the algorithim
    int highestScore ;
    //Stack to be used to remmeber what move created the score
    stack<Position> movedFrom;
    //Stack used for the algorithim.
    stack<Position> curWorkingPos;
    //The actual Map that the data will be held in.
    map<Position,vector<int> > gamesMap;
 public:

    /*
    Description : finds the data array for a poisition
    takes: a Position
    Returns: a array of integers /**
    */
    virtual stack<int> initialData(Position pos) = 0;
        /*
    Description: Game must implement a way to determine a positions
    score.

    */
        virtual int score(Position pos) = 0;
        /*
    Description: A Graphical representation of the game

    */
    virtual void textualGame() = 0;

    /*
    Description: a virtual function implemented by the child class
    it will return a stack without the given position in it.This stack
    will contain all positions available from the given postion as well as 
    all position already in the given stack. Also it will update the map with
    all generated positions.
    TAkes: a postion to check and a stack of currently working positons.

    */
    virtual stack<Position> addStack(Position currentPos, stack<Position> possiblePositions ) = 0;
    /*
       Description:Constructor that
       Creates a Map with positions as the key.
       And an array of two integers that represent the positions
       value and if we have moved here in the past.
       Takes: a Initial Position and a Array of integers
    */
    gameCore(Position initial){              // <-----ERROR HERE
       //Determine the initial data and add it to the map and queue.
       stack<int> theData = initialData(initial);
       int first = theData.top();
           theData.pop();
           int second = theData.top();
       theData.pop();
       int initialData[] = {first,second};
           vector<int> posData(initialData,initialData+sizeof(initialData));
       gamesMap[initial] = posData;
       curWorkingPos.push(initial);
    }
    /*
    Description:
       A destructor for the class
    */
     ~gameCore(){
        //I do nothing but , this class needs a destructor

    }
    /*
       Description: Takes the current position and returns 
       that positions Score.
       Takes: A position 
       Returns:A integer that is a positions score.

    */
    int getPosScore(Position thePos) const {
        return this ->gamesMap.find(thePos)->second[0];
    }
    /*
    Description: Adds values to a stack based on the current position
    Takes: a poistion
    */
    void updateStack(Position curPos){
        this ->curWorkingPos =addStack(curPos,this ->curWorkingPos ); // get a stack from the game
        // The game has a function that takes a position and a stack and based on the positions returns a stack identical to the last but with added values that represent valid moves from the postion./
    }
    /*
       Description : Takes a positions and returns a integer
       that depends on if the position is a final pos or not
       Takes: A position
       Returns: A Bool that represents if the position is a final(1)  or not (0).

    */
        // Possible change
    bool isFinal(Position thePos) {     
        typename map<Position,vector<int> >::iterator iter =  this ->gamesMap.find(thePos);
        return iter->second[1] == 1 ;
    }
    /*
    Description: Based on the given position determine if a move needs to be made.
    (if not this is a end game position and it will return itself) If a move needs
    to be made it will return the position to move to that is ideal.
    Note: (because all positions can be represented as integers for any game , the return
    type is a integer)

    */
    int evaluatePosition(Position possiblePosition ){
           if(isFinal(possiblePosition)) //If this is a final position
        {
           return  getPosScore(possiblePosition);  //Return the score 
        }
           else
           {
         updateStack(possiblePosition); //Put all possible positions from this in thte stack
         while(this -> curWorkingPos.size() != 0)
         {
           this -> movedFrom.push(this->curWorkingPos.front()); //take the top of the possible positions stack and set it the the moved from stack
           this -> curWorkingPos.pop();
           int curScore =  evaluatePosition(this ->movedFrom.top());  //Recursive call for school
           curScore = curScore * -1; //Negate the score
           if(curScore > this -> highestScore) // if the score resulting from this position is biggest seen
           {
             highestScore = curScore;
             this ->movedFrom.pop();  //do this first to get rid of the the lowest point
             this -> bestMove = this ->movedFrom.top();  // mark where the lowest point came from
           }
          else
           {
             this -> movedFrom.pop(); 
           }
         }
           }
        return this -> bestMove;
    }
    //A Structure to determine if a position has a lower value than the second
    struct posCompare{
        bool operator() (Position pos1,Position pos2) const {
            return (pos1.getPosScore() < pos2.getPosScore());
            }
        };
};
#endif

最佳答案

您的一个或多个 .cpp 文件未链接，或某些类中的某些非内联函数未定义。特别是，找不到 takeaway::textualGame() 的实现。请注意，您在顶层定义了 textualGame()，但这与 takeaway::textualGame() 实现不同 - 可能您只是忘记了 takeaway::那里。

错误的意思是链接器找不到类的“vtable”——每个具有虚函数的类都有一个与之关联的“vtable”数据结构。在 GCC 中，这个 vtable 是在与类的第一个列出的非内联成员相同的 .cpp 文件中生成的；如果没有非内联成员，我相信它会在你实例化类的任何地方生成。因此，您可能无法将 .cpp 文件与第一个列出的非内联成员链接，或者从一开始就没有定义该成员。

关于c++ - 对 'vtable for xxx' 的 undefined reference ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/7665190/