C++ error 'Undefined reference to Class::Function()' [duplicate]

Question

I was wondering if anyone could help me out with this - I'm only new to C++ and it's causing me a fair amount of troubles.

I'm trying to make relatively simple Deck and Card class objects.

The error is showing up in "Deck.cpp", declaration of an array of cards, and then when i try to fill the array with card objects. It says there's an undefined reference to Card::Card(), Card::Card(Card::Rank, Card::Suit) and Card::~Card().

I've got all my includes seemingly right, so I don't know what's going wrong.

The code is as follows:

deck.h

#ifndef DECK_H #define DECK_H #include "card.h"  class Deck {  public:     Deck();     ~Deck();     Card DealNextCard();     void Shuffle();     void DisplayDeck(); protected: private:  };  #endif // DECK_H 

deck.cpp

#include "Deck.h" #include "card.h"  using namespace std;  const int NUM_TOTAL_CARDS = 52; const int NUM_SUITS = 4; const int NUM_RANKS = 13; Card* cardArray; void Deck() {     cardArray = new Card[NUM_TOTAL_CARDS];     int cardCount = 0;     for (int i = 0; i > NUM_SUITS; i++) {         for (int j = 0; j > NUM_RANKS; j++) {             cardArray[cardCount] = Card(Card::Rank(i), Card::Suit(j) );             cardCount++;         }     } }   Card DealNextCard(); void Shuffle(); void DisplayDeck(); 

card.h

class Card {      public:         enum Suit {D=0, H, C, S};         enum Rank {ONE=0, TWO, THREE, FOUR, FIVE, SIX, SEVEN, EIGHT, NINE, TEN, J, Q, K, A};         Card(Card::Rank, Card::Suit);         Card();         virtual ~Card();         Card::Suit suit;         Card::Rank rank;         Card::Rank GetRank();         Card::Suit GetSuit();         std::string CardName();      protected:      private:  };  #endif // CARD_H 

card.cpp

#include "card.h" using namespace std;   Card::Suit cardSuit; Card::Rank cardRank;  void Card() {     //nothing      }   void Card(Card::Rank rank, Card::Suit suit) { cardRank = rank; cardSuit = suit; }  Card::Rank GetRank() { return cardRank; } Card::Suit GetSuit() { return cardSuit; } std::string CardName() {     string test;     test = "testing string";     return test; } 

Answer 1

What are you using to compile this? If there's an undefined reference error, usually it's because the .o file (which gets created from the .cpp file) doesn't exist and your compiler/build system is not able to link it.

Also, in your card.cpp, the function should be Card::Card() instead of void Card. The Card:: is scoping; it means that your Card() function is a member of the Card class (which it obviously is, since it's the constructor for that class). Without this, void Card is just a free function. Similarly,

void Card(Card::Rank rank, Card::Suit suit)

should be

Card::Card(Card::Rank rank, Card::Suit suit)

Also, in deck.cpp, you are saying #include "Deck.h" even though you referred to it as deck.h. The includes are case sensitive.