如何创建一个类，它是C++中另一个类的向量

Question

感谢阅读我的问题。

我正试图开始编写一个使用一副卡片的程序，因为我想学习如何使用类。我决定创建一个存储套装和价值的类，比如：

#ifndef CARD_H
#define CARD_H
class Card {        
public:
//here are the individual card values
int _suit;
int _value;
Card(int suit, int value);
};
#endif

#include "card.h"
//define suits
const int spades = 0;
const int clubs = 1;
const int hearts = 2;
const int diamonds = 3;
//define face cards
const int jack = 11;
const int queen = 12;
const int king = 13;
const int ace = 14;
Card::Card(int suit, int value){
_suit = suit;
_value = value;
}

然后我决定创建一个牌组类，在该类中，通过分配0-3(套装)的值和2-14(牌的排名)的值来初始化我的牌。我还将卡片添加到我定义的向量中以容纳它们，就像这样：

#ifndef DECK_H
#define DECK_H
#include <vector>
class Deck {
public:
std::vector<Card> _deck(51);
Deck();
};
#endif

#include <iostream>
#include <vector>
#include "card.h"
#include "deck.h"
const int all_suits = 4 - 1;
const int all_values = 14;
Deck::Deck(){
int i = 0;
for (int j = 0; j <= all_suits; ++j) {
//begin with 2 because card can't have value 0
for (int k = 2; k <= all_values; ++k) {
_deck[i] = Card(j, k);
++i;
}
}
}   

当我尝试测试程序时，这不知何故给了我问题：

#include <iostream>
#include <vector>
#include "card.h"
#include "deck.h"
int main() {
Deck new_deck = Deck();
std::cout << new_deck._deck[4]._value;
return 0;
}

当我尝试运行代码时，会出现以下错误：

In file included from main.cpp:6:
./deck.h:8:27: error: expected parameter declarator
std::vector<Card> _deck(51);
^
./deck.h:8:27: error: expected ')'
./deck.h:8:26: note: to match this '('
std::vector<Card> _deck(51);
^
main.cpp:22:24: error: reference to non-static member function must be called; did you mean to call it with no arguments?
std::cout << new_deck._deck[4]._value;
~~~~~~~~~^~~~~
()
3 errors generated.
In file included from deck.cpp:8:
./deck.h:8:27: error: expected parameter declarator
std::vector<Card> _deck(51);
^
./deck.h:8:27: error: expected ')'
./deck.h:8:26: note: to match this '('
std::vector<Card> _deck(51);
^
deck.cpp:18:4: error: reference to non-static member function must be called; did you mean to call it with no arguments?
_deck[i] = Card(j, k);
^~~~~
()
3 errors generated.

老实说，我不太确定发生了什么。我非常仔细地学习了我在网上看到的一个课程示例。如果有人能帮我找到问题，我将不胜感激。对不起，我对此有点陌生，可能犯了一些愚蠢的错误。我真的很感谢你花时间和耐心阅读并帮助我。

Answer 1

您的问题在于_deck:的声明

class Deck {
public:
std::vector<Card> _deck(51);

在这里，您试图声明_deck并调用构造函数，但不能从类成员初始化器中这样做。对于没有构造函数的数据成员，可以这样做，例如：

class Deck {
public:
int no_of_cards = 51;
std::vector<Card> _deck;

您需要使用构造函数来初始化_deck(就像您已经在做的一样：

Deck::Deck() {
_deck.reserve(51);
int i = 0;
for (int j = 0; j <= all_suits; ++j) {
//begin with 2 because card can't have value 0
for (int k = 2; k <= all_values; ++k) {
_deck.push_back(Card(j, k));
++i;
}
}
}

并将您的_deck声明保留为：

class Deck {
public:
std::vector<Card> _deck;