如何通过引用将地图传递给函数？ Visual Stu@R_502_410@ 2010给我一个未解决的外部错误.目前,我有以下简化代码：
void function1(){
map<int,int> * my_map = new map<int,int>();
function2(*my_map);
}
void function2(map<int,int> &temp_map){
//do stuff with the map
}
这里有类似问题的几个答案,但是他们使用typedef并将std ::添加到定义的开头,但我真的不知道为什么.
int ComputerPlayer::getBestMoves(){
//will return the pit number of the best possible move.
//map to hold pit numbers and rankings for each possible pit number.
//map<pitNumber,rank> only adds pit numbers to map if they have seeds in them.
std::map<int,int> possiblePits; //map
std::map<int,int>::iterator it; //iterator for map
for(int index = 1; index <= getBoardSize(); index++){
if(_board.getPitValue(index) > 0){
possiblePits.insert( pair<int,int>(index,0) );
}
}
int tempBoardSize = _board.getBoardSize();
//loop that will analyze all possible pits in the map
for(it = possiblePits.begin(); it != possiblePits.end(); it++){
Board tempBoard = _board;
int pitNum = it->first;
int score = analyzePlay(pitNum,tempBoard,possiblePits);
}
return 0;
}
int analyzePlay(int pitNum,Board tempBoard,std::map<int,int> &possibleMoves){
int tempBoardSize = tempBoard.getBoardSize();
int tempSeeds = tempBoard.getPitValue(pitNum);
int lastPitSown;
tempBoard.setPitToZero(pitNum);
for(int index = 1; index <= tempSeeds; index++){
if(pitNum == tempBoardSize * 2 + 1){
//skips over human's score pit
pitNum += 2;
lastPitSown = pitNum;
tempBoard.incrementPit(pitNum);
}
else{
pitNum++;
lastPitSown = pitNum;
tempBoard.incrementPit(pitNum);
}
}
if(tempBoard.getPitValue(lastPitSown) == 1 && lastPitSown >= tempBoardSize + 2 && lastPitSown <= tempBoardSize * 2 + 1){
//turn ends. last seed sown into empty pit on opponent side.
}
else if(tempBoard.getPitValue(lastPitSown) > 1 && lastPitSown != tempBoardSize + 1){
//keep playing with next pit. last seed was sown into non-empty pit.
}
else if(lastPitSown == tempBoardSize + 1){
//extra turn. last seed sown into score pit.
}
else if(tempBoard.getPitValue(lastPitSown) == 1 && lastPitSown != tempBoardSize + 1 && lastPitSown <= tempBoardSize && lastPitSown >= 1 ){
//turn ends. last seed sown into empty pit on your side. capture.
}
return 0;
}
我得到的错误：
Error 1 error LNK2019: unresolved external symbol "public: int __thiscall ComputerPlayer::analyzePlay(int,class Board,class std::map<int,int,struct std::less<int>,class std::allocator<struct std::pair<int const,int> > > &)" (?analyzePlay@ComputerPlayer@@QAEHHVBoard@@AAV?$map@HHU?$less@H@std@@V?$allocator@U?$pair@$$CBHH@std@@@2@@std@@@Z) referenced in function "public: int __thiscallComputerPlayer::getBestMoves(void)" (?getBestMoves@ComputerPlayer@@QAEHXZ) C:\Users\Josh\DropBox\Congkak_2\Congkak_2\ComputerPlayer.obj Error 2 error LNK1120: 1 unresolved externals C:\Users\Josh\DropBox\Congkak_2\Debug\Congkak_2.exe
解决方法
两件事情：
>添加#include< map>在顶部,并使用std :: map而不是地图.
>定义function2上面的function1或者至少在function1上面声明function2.
以下是两个方面的做法：
#include<map>
void function2(std::map<int,int> &temp_map); //forward declaration
void function1(){
std::map<int,int> my_map; //automatic variable
//no need to make it pointer!
function2(my_map);
}
void function2(std::map<int,int> &temp_map){
//do stuff with the map
}
还要注意,尽可能避免新的.默认使用自动变量,除非你有很强的理由不使用它.
自动变量很快,代码看起来整齐干净.使用它们,更容易编写异常安全的代码.
编辑：
现在当你发布错误,你也意识到,
I forgot to add the Class that the function was part of to the beginning of it. as in: Player::function2(std::map<int,int> &temp_map){}
正如您在评论中所说.
