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我正在尝试制作一个Question对象。Question作为班级，但我收到一个错误，即：

错误 1 ​​错误 C2440：“正在初始化”：无法从转换Questions *为Questions

我正在尝试制作一个对象，以便我可以将它放入一个multimap类型<int, Questions>

这是我的代码：

#include <iostream>
#include "Questions.h"
using namespace std;

Questions::Questions() {}
Questions::Questions(string question,string correctAnswer, string wrongAnswer1,string wrongAnswer2,string wrongAnswer3) {}

void Questions::questionStore() {
    Questions q1 = new Questions("Whats the oldest known city in the world?", "Sparta", "Tripoli", "Rome", "Demascus");
    string q2 = ("What sport in the olympics are beards dissallowed?", "Judo", "Table Tennis", "Volleyball", "Boxing");
    string q3 = ("What does an entomologist study?", "People", "Rocks", "Plants", "Insects");
    string q4 = ("Where would a cowboy wear his chaps?", "Hat", "Feet", "Arms", "Legs");
    string q5 = ("which of these zodiac signs is represented as an animal that does not grow horns?", "Aries", "Tauris", "Capricorn", "Aquarius");
    string q6 = ("Former Prime Minister Tony Blair was born in which country?", "Northern Ireland", "Wales", "England", "Scotland");
    string q7 = ("Duffle coats are named after a town in which country?", "Austria", "Holland", "Germany", "Belgium");
    string q8 = ("The young of which creature is known as a squab?", "Horse", "Squid", "Octopus", "Pigeon");
    string q9 = ("The main character in the 2000 movie ""Gladiator"" fights what animal in the arena?", "Panther", "Leopard", "Lion", "Tiger");

    map.insert(pair <int, Questions>(1, q1));
    map.insert(pair <int, string>(2, q2));
    // map.insert(pair<int,string>(3, q3));
    for (multimap <int, string, std::less <int> >::const_iterator iter = map.begin(); iter != map.end(); ++iter)
        cout << iter->first << '\t' << iter->second << '\n';
}
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3 回答 3

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该new表达式为您提供了一个指向您已动态分配的对象的指针。你需要做Questions* q1 = new Questions(...);。但是，如果您不需要动态分配（最终将对象复制到地图中），请不要打扰。做吧Questions q1(...);。

据推测，您将更改以下行（q2、q3等）以匹配，但它们并没有按照您的预期进行。将(..., ..., ...)评估为此逗号分隔列表中最右边的项目。所以你的q2线相当于string q2 = "Boxing";.

于 2012-12-18T23:51:06.670 回答
1

Questions q1 = new Questions是不正确的语法。

从 map.insert(pair <int, Questions>(1, q1));我可以看到你的map值类型是 Questions 对象而不是 Questions 指针，所以它应该是

Questions q1 = Questions ("Whats the oldest known city in the world?", "Sparta" , "Tripoli" , "Rome", "Demascus");

此外，您的变量映射与作为 STL 容器的 std::map 同名，建议您使用其他名称，例如question_map：

编辑

为了让<< iter->second您需要重载operator<<问题类型。

std::ostream& operator<<(const std::ostream& out, const Questions& q)
{
    out << q.question;  // I made up this member as I can't see your Questions code
    return out;
}
于 2012-12-18T23:52:02.183 回答
0

您的方法的第一行questionScore是问题：

Questions q1 = new Questions ...

new x返回指向x对象的指针，因此q1应定义为指针。

Questions * q1 = new Questions ...
于 2012-12-18T23:51:50.233 回答