简单的C ++卡程序。 未知错误

Question

Ok so I am new to C++ and trying to write I simple program that is a deck of cards. But I get the errors: "unresolved externals". I have a feeling it has something to do with the instantiation in the constructor. A quick look would be appreciated.

#include "Card.h"
#include "Deck.h"

Deck:: Deck()
{
  this -> currentCard=0;

  this -> index = 0;

    for(int i=0;i<4;i++)
    {
        for(int j =0; j < 13;j++)
       {
          deck[index].setVal(i);
      deck[index].setSuit (j);
          index++;
        }
    }
 }


void Deck::shuffle()
{
  //implementation
  }
Card Deck:: dealCard()
{
  //implementation
   }


int main (){}

my header file is:

#include "Card.h"

class Deck
{
public:
Deck();
void shuffle();
Card dealCard();




private:
Card deck [52];
int currentCard;
int index;
};

Answer 1

It error means that you have unresolved external symbols .

Now Symbols can be anything from Variables, Classes, Member functions.

Why they are unresolved is because may be some part of your code (or libraries that you are using) rely on these symbols and they are not being found because you are not linking the correct library or implementing them.

Please try compiling all your source files and make sure there are no Symbols(Variables, Classes, Member Functions etc) missing.

Answer 2

Card class seems to be undeclared. You probably want to do it in Card.h file. You can forward-declare it by simply typing class Deck; , but remember it's just a place-holder that must be resolved somewhere anyway.

Answer 3

Usually 'Unresolved externals' points to the unresolved symbol:

error LNK2001: unresolved external symbol "the symbol that wasn't resolved"

This will show you what the linker is missing.

Hope this helps, Yaron