如何通过引用将地图传递给函数？ Visual Studio 2010给我一个未解决的外部错误.目前,我有以下简化代码：
@H_@R_301_450@_2@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.
@H_@R_301_450@_2@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：
@H_@R_301_450@_2@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：
@H_@R_301_450@_2@#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.
