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c++stlmultimap

Error when trying to make an object


I'm trying to make a Question object. Question being the class but I'm getting an error which is:

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

I'm trying to make an object so I could put it into a multimap of type <int, Questions>

Here is my code:

#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';
}

Solution

  • Questions q1 = new Questions is incorrect syntax.

    From map.insert(pair <int, Questions>(1, q1)); I can see your map value type is Questions object instead of Questions pointer, so it should be

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

    Also your variable map is having the same name as std::map which is a STL container, suggest you use another name, for example: question_map;

    Edit

    To allow << iter->second you need to overload operator<< for Questions type.

    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;
    }