Question

我有一张带卡片的矢量，我需要找到卡片并将其删除。我尝试了下面的代码但是我收到了错误： binary＆＃39; ==＆＃39;：找不到运算符，它采用类型为＆＃39; Card＆＃39; 的左手操作数

代码对我有意义。你能给我一些如何使其有效的提示吗？谢谢！

void Player::RemoveCardFromPackage(const Card& cardToBeRemoved)
{    
    std::vector<Card>::iterator position = std::find(CadrVector.begin(), CadrVector.end(), cardToBeRemoved);
    if (position != CadrVector.end())
    {
        CadrVector.erase(position);
    }
}

Answer 1

您希望std::find()如何比较自定义类型CadrVector的两个元素？当其中两个元素被认为是相等的而不是时？你必须定义它。

所以要么将比较器传递给std::find()的第四个参数，要么重载你类型的==运算符。

Answer 2

您可以使用自定义比较功能尝试find_if：

#include <iostream>
#include <algorithm>
#include <vector>

class Card
{
    int c;
public:
    Card(int c): c(c) {}
    int GetC() const { return c; }
};

std::vector<Card> CardVector;

class Player 
{
public:
    void RemoveCardFromPackage(const Card& cardToBeRemoved);
};

void Player::RemoveCardFromPackage(const Card& cardToBeRemoved)
{

    auto found = std::find_if(CardVector.begin(), CardVector.end(), [&cardToBeRemoved](Card const &card) 
    {
        return cardToBeRemoved.GetC() == card.GetC();
    });

    if (found != CardVector.end())
    {
        CardVector.erase(found);
    }
}

int main()
{
    Player p;
    Card c1(1);
    CardVector.push_back(c1);
    Card c2(2);
    CardVector.push_back(c2);
    Card c3(3);
    CardVector.push_back(c3);

    std::cout << "Before:\n";
    for (size_t i = 0; i < CardVector.size(); ++i)
        std::cout << "Card C: " << CardVector[i].GetC() << " ";

    p.RemoveCardFromPackage(c2);

    std::cout << "\n\nAfter:\n";
    for (size_t i = 0; i < CardVector.size(); ++i)
        std::cout << "Card C: " << CardVector[i].GetC() << " ";

    return 0;
}

打印：

Before:
Card C: 1 Card C: 2 Card C: 3

After:
Card C: 1 Card C: 3

C ++按值擦除矢量元素

2 个答案: