Question

以下引发了编译时错误。我不确定如何调用一个对象重载运算符＆lt;＆lt;在另一个对象中＆lt;＆lt;运营商？如果有人能指出我做错了什么，那真的很有帮助。谢谢你的时间！

card.cpp：

#include "card.h"
#include <iostream>

ostream& operator<<(ostream &out, Card &cCard)
{
    out << cCard.getValueString() 
        << " OF " 
        << cCard.getSuitString() 
        << "S\n";
    return out;
}

string Card::getValueString()
{
    Value value = getValue();
    switch(value) 
    {
        case TWO:           return "TWO";
        case THREE:         return "THREE"; 
        case FOUR:          return "FOUR"; 
        case FIVE:          return "FIVE";
        case SIX:           return "SIX";
        case SEVEN:         return "SEVEN";
        case EIGHT:         return "EIGHT";
        case NINE:          return "NINE";
        case TEN:           return "TEN";
        case JACK:          return "JACK";
        case QUEEN:         return "QUEEN";
        case KING:          return "KING";
        case ACE:           return "ACE"; 
        case NONE_VALUE:    return "NONE_VALUE";
        default:            return "UNKNOWN VALUE";  
    };
}

string Card::getSuitString()
{
    Suit suit = getSuit();
    switch(suit) 
    {
        case SPADE:         return "SPADE";
        case HEART:         return "HEART"; 
        case CLUB:          return "CLUB"; 
        case DIAMOND:       return "DIAMOND";
        case NONE_SUIT:     return "NONE_SUIT";
        default:            return "UNKNOWN SUIT";
    };
}

card.h

#pragma once
#include <iostream>
using namespace std;

 enum Suit  { 
                SPADE, 
                HEART, 
                CLUB, 
                DIAMOND,
                NONE_SUIT 
            };

 enum Value  { 
                TWO=2, 
                THREE, 
                FOUR, 
                FIVE,
                SIX,
                SEVEN,
                EIGHT,
                NINE,
                TEN,
                JACK,
                QUEEN,
                KING,
                ACE, 
                NONE_VALUE
            };

    class Card
    {

        public:
            Card() : m_suit(NONE_SUIT), m_value(NONE_VALUE) { };
            Card(Suit suit, Value value) : m_suit(suit), m_value(value) { };
            Value getValue() { return m_value; };
            Suit getSuit() { return m_suit; };
            void setValue(Value value) { m_value = value; };
            void setSuit(Suit suit) { m_suit = suit; };
            string getValueString();
            string getSuitString();
            friend ostream& operator<<(ostream &out, Card &cCard);
        private:
            Suit m_suit;
            Value m_value;      
    };

hand.cpp：

#include "hand.h"
#include "card.h"

ostream& operator<<(ostream &out, Card &cCard);

Hand::Hand() 
{

}

Card Hand::getCard(int cardIndex) 
{
    if(cardIndex == 0 || cardIndex == 1)
    {
        return cards[cardIndex];
    }
    else
    {
        cout << "Card index out of bounds.\n";
    }

    return Card(NONE_SUIT, NONE_VALUE);
}

void Hand::setCard(int cardIndex, Suit suit, Value value)
{
    if(cardIndex == 0 || cardIndex == 1)
    {
        cards[cardIndex].setValue(value);
        cards[cardIndex].setSuit(suit);
    }
    else
    {
        cout << "Card index out of bounds.\n";
    }
};

ostream& operator<<(ostream &out, Hand &cHand)
{
    out << cHand.getCard(0) 
        << "\n"
        << cHand.getCard(1);
    return out;
}

hand.h：

#pragma once
#include <iostream>
#include "card.h"
using namespace std;

class Hand
{
    public:
        Hand();
        void setCard(int cardIndex, Suit suit, Value value);
        Card getCard(int cardIndex);
        friend ostream& operator<<(ostream &out, Hand &cHand);
    private:
        Card cards[2];      
};

错误如下：

hand.cpp：在函数'std :: ostream＆amp; operator＆lt;＆lt;（std :: ostream＆amp;，Hand＆amp;）'： hand.cpp：40：错误：'out＆lt;＆lt;＆lt;＆lt;＆lt;＆lt;＆lt;＆lt;＆lt; （（手*）昌德） - ＆GT;手:: getCard（0）” /usr/include/c++/4.2.1/ostream:112：注意：候选人是：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp;（*）（std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp;））[with _CharT = char， _Traits = std :: char_traits] /usr/include/c++/4.2.1/ostream:121：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（std :: basic_ios＆lt; _CharT，_Traits＆gt;＆amp;（*）（std :: basic_ios＆lt; _CharT，_Traits＆gt;＆amp;））[with _CharT = char， _Traits = std :: char_traits] /usr/include/c++/4.2.1/ostream:131：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（std :: ios_base＆amp;（*）（std :: ios_base＆amp;））[with _CharT = char，_ Traits = std :: char_traits] /usr/include/c++/4.2.1/ostream:169：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（long int）[with _CharT = char，_Traits = std :: char_traits] /usr/include/c++/4.2.1/ostream:173：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（long unsigned int）[with _CharT = char，_Traits = std :: char_traits] /usr/include/c++/4.2.1/ostream:177：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（bool）[with _CharT = char，_Traits = std :: char_traits] /usr/include/c++/4.2.1/bits/ostream.tcc:92:note:std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（short int）[with _CharT = char，_Traits = std :: char_traits] /usr/include/c++/4.2.1/ostream:184：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（short unsigned int）[with _CharT = char，_Traits = std :: char_traits] /usr/include/c++/4.2.1/bits/ostream.tcc:106：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（int）[with _CharT = char，_Traits = std :: char_traits] /usr/include/c++/4.2.1/ostream:195：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（unsigned int）[with _CharT = char，_Traits = std :: char_traits] /usr/include/c++/4.2.1/ostream:204：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_ Traits＆gt; :: operator＆lt;＆lt;（long long int）[with _CharT = char，_Traits = std :: char_traits] /usr/include/c++/4.2.1/ostream:208：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（long long unsigned int）[with _CharT = char，_ Traits = std :: char_traits] /usr/include/c++/4.2.1/ostream:213：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（double）[with _CharT = char，_Traits = std :: char_traits] /usr/include/c++/4.2.1/ostream:217：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_ Traits＆gt; :: operator＆lt;＆lt;（float）[with _CharT = char，_Traits = std :: char_traits] /usr/include/c++/4.2.1/ostream:225：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（long double）[with _CharT = char，_Traits = std :: char_traits] /usr/include/c++/4.2.1/ostream:229：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（const void *）[with _CharT = char，_ Traits = std :: char_traits] /usr/include/c++/4.2.1/bits/ostream.tcc:120：注意：std :: basic_ostream＆lt; _CharT，_Traits＆gt;＆amp; std :: basic_ostream＆lt; _CharT，_Traits＆gt; :: operator＆lt;＆lt;（std :: basic_streambuf＆lt; _CharT，_Traits＆gt; *）[with _CharT = char，_Traits = std :: char_traits] hand.cpp：4：注意：std :: ostream＆amp;运算符＆lt;＆lt;（std :: ostream＆amp;，Card＆amp;） hand.cpp：38：注意：std :: ostream＆amp; operator＆lt;＆lt;（std :: ostream＆amp;，Hand＆amp;）

关于我遗失的任何想法？

Answer 1

您的operator <<函数应该通过const引用获取右侧参数。它告诉你它不能将getCard返回的临时值绑定到运算符的非const引用参数。

令人难以置信的长错误消息是因为在任何时候范围内都有<<非常多的重载，并且编译器将所有这些重载列为“我试过这个但是它不起作用。“

调用成员的重载＆lt;＆lt; C ++中的运算符

1 个答案: