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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）和一个从gameCore继承的类（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，但我已经明确标记了错误发生的位置）takeaway.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
外卖.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;
}
游戏核心.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
原文由 TacticalMin 发布，翻译遵循 CC BY-SA 4.0 许可协议
第一组错误，对于缺少的 vtable，是因为你没有实现
takeaway::textualGame()引起的；相反，您实现了一个非成员函数textualGame()。我认为添加缺少的takeaway::会解决这个问题。最后一个错误的原因是您正在从
initialData()的构造函数调用虚函数gameCore。在这个阶段，虚函数是根据当前正在构造的类型（gameCore） 而不是 派生最多的类（takeaway）来调度的。这个特定的函数是纯虚函数，因此在这里调用它会产生未定义的行为。两种可能的解决方案：
gameCore的初始化代码移出构造函数并放入单独的初始化函数中，该函数必须在对象完全构造 后 调用；或者gameCore分成两个类：一个由takeaway实现的抽象接口和一个包含状态的具体类。首先构造takeaway，然后将它（通过对接口类的引用）传递给具体类的构造函数。我会推荐第二种，因为它是向更小的类和更松散的耦合方向发展，并且更难错误地使用这些类。第一个更容易出错，因为无法确保正确调用初始化函数。
最后一点：基类的析构函数通常应该是虚拟的（以允许多态删除）或受保护的（以防止无效的多态删除）。