c++ - 尝试制作对象时出错

Question

我正在尝试制作 Question目的。 Question作为类(class)，但我收到一个错误:

Error 1 error C2440: 'initializing' : cannot convert from Questions * to Questions

我正在尝试制作一个对象，以便将其放入 multimap 中类型 <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';
}

Answer 1

Questions q1 = new Questions是不正确的语法。

来自 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");

另外你的变量映射与std::map同名，它是一个STL容器，建议你使用另一个名称，例如:question_map ;

编辑

允许<< iter->second你需要重载 operator<<对于问题类型。

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;
}