使用STD ::查找从向量中选择项目

三个问题。

一个，您的操作员应被声明为：

bool operator==(const aItem& other) const

两个，在此代码中：

find(inventory.begin(), inventory.at(choice), healingPotion) != inventory.end())

您没有搜索从begin()到end()的整个向量 - 您仅搜索从begin()到at(choice)，其中at(choice)指向您搜索集的一past-the-end。因此，您要么要这样做：

find(&inventory.at(0), &inventory.at(choice), healingPotion) != &inventory.at(choice))

或这个...

find(inventory.begin(), inventory.end(), healingPotion.itemName) != inventory.end())

编辑三，您正在尝试将苹果与橙色进行比较。您正在搜索aItem对象的vector来查找匹配的aItem对象，但是您发送到find的参数不是aItem对象，它是aItem数据成员之一。

您应该搜索匹配的项目，例如：

find( inventory.begin(), inventory.end(), healingPotion ) != inventory.end() )
                                            ^^^^^^^^

在C 03中，您可以提供一个函子：

#include <functional>
struct match_name : public std::unary_function<aItem, bool>
{
    match_name(const string& test) : test_(test) {}
    bool operator()(const aItem& rhs) const
    {
        return rhs.itemName == test_;
    }
private:
  std::string test_;
};

...然后使用find_if搜索匹配：

find_if( inventory.begin(), inventory.end(), match_name(healingPotion.itemName) ) // ...

在C 11中，您可以使用闭合来简化此烂摊子：

string test = healingPotion.itemName;
if( find_if( inventory.begin(), inventory.end(), [&test](const aItem& rhs)
{
    return test == rhs.itemName;
}) == inventory.end() )
{
  // not found
}

要添加到约翰·迪布林（John Dibling）的答案中，最后一部分是您正在寻找名称，而不是AITEM。

所以要么需要：

find(inventory.begin(), inventory.end(), healingPotion) != inventory.end();

其中operator ==定义为：

bool operator==(const aItem& other) const
{
   return itemName == other.itemName;
}

否则您需要让操作员==取一个字符串：

find(inventory.begin(), inventory.end(), healingPotion.itemName) != inventory.end();

其中operator ==定义为：

bool operator==(const std::string& name) const
{
   return itemName == name;
}

而不是：

case 1:
        cout << "Which item would you like to use?" << endl;
        int a = 1;
        for( vector<aItem>::size_type index = 0; index < inventory.size(); index++ ) 
        {
            cout << "Item " << a << ": " <<  inventory[index].itemName << endl;
            a+= 1;
        }
        cout << "MAKE YOUR CHOICE." << endl << "Choice: ";
        cin >> choice;
        if (find(inventory.begin(), inventory.at(choice), healingPotion.itemName) != inventory.end())
            cout << "You used a healing potion!";
        else
            cout << "FIERY BALLS OF JOY!";
        break;
    case 2:
        cout << "Such a jerk, you are." << endl;
            break;
    }

我忽略了意识到向量的奇观之一是能够直接访问价值的能力 - 瑞安·古斯里（Ryan Guthrie）在他的评论中提到了这一点，但我发现了一个更简单的"答案"。即：

case 1:
    cout << "Which item would you like to use?" << endl;
    //TODO: Learn what the hell the following line actually means.
    for( vector<aItem>::size_type index = 0; index < inventory.size(); index++ ) 
    {
        //Makes a numerical list.
        cout << "Item " << index + 1 << ": " <<  inventory[index].itemName << endl;
        a+= 1;
    }
    cout << "MAKE YOUR CHOICE." << endl << "Choice: ";
    cin >> choice;
    //Cannot define this outside of the statement, or it'll initialize to -1
    invVecPos = (choice - 1);
    //This checks for an invalid response. TODO: Add in non-int checks. 
    if ((invVecPos) >= inventory.size())
    {
        cout << "Choice out of bounds. Stop being a dick." << endl;
    }
    //If the choice is valid, proceed.
    else
    {
        //checking for a certain item type.
        if(inventory[invVecPos].itemType == "ITEM_HEALTHPOT")
        {
            cout << "You used a healing potion!" << endl;
            //this erases the potion, and automagically moves everything up a tick.
            inventory.erase (inventory.begin() + (invVecPos));
        }
        else if(inventory[invVecPos].itemType == "ITEM_FIREPOT")
        {
            cout << "FIERY BALLS OF JOY!" << endl;
        }
        else
        {
            //error-handling! Whee!
            cout << "Invalid Item type" << endl;
        }
    }

    break;
case 2:
    cout << "Why do you have to be so difficult? Pick 1!" << endl;
    break;

谢谢Ryan-随着您的兴趣，我可以在其他地方查看并找到所需的代码！对"固定"代码进行了大量评论，因此遇到问题的其他任何人都应该能够收集他们的需求！