c++ multiple choice question created by blongho - https://repl.it/@blongho/c-multiple-choice-question

Answer.hpp

/**
* @file  : Answer.hpp
* @author: blongho
* @since : 2018-11-25
* @brief : A class to hold an Answer for use in a multiple choice Question
**/
#ifndef ANSWER_H
#define ANSWER_H

#include <iostream>

/**
* This class was originally intended to be a template but it resulted to over complication
* Just make sure all your answers values are std::string. It makes a whole lot 
* easier implementation and use
*
* Usage:
*       Answer answer1("value"); // results to value=value, isCorrect() = false;
*       Answer answer2("2", true); // results to value=2, isCorrect() = true;
*       Answer answer3("true", true) // results to value=true, isCorrect() = true;
*       Answer answer4("5.6", false); // results to value=5.6, isCorrect() = false;
*/ 
class Answer{
  private:
    std::string value;
    bool correct;

  public:
    Answer()=default;
    Answer(const std::string &val, bool status = false){
      value = val;
      correct = status;
    }

  bool isCorrect() const{
    return correct;
  }

  std::string getValue() const{
    return value;
  }

  void setValue(const std::string &val){
    value = val;
  }

  void setCorrect(const bool &status){
    correct = status;
  }

  void printOn(std::ostream &os=std::cout){
    os << "ANSWER: value="  << value << ", is correct? " << std::boolalpha << correct << "\n";
  }

  // to be used in Question class where we display just the option
  void display(std::ostream &os=std::cout){
    os <<  value << "\n";
    }
};

#endif

Main.cpp

/**
* @file  : Main.cpp
* @author: blongho
* @since : 2018-11-25
* @brief : Demonstration of use of Question and Answer classes
**/
#include <iostream>
#include "Question.hpp"
#include <string> 
 
int main() {
  
  Answer op1("2"), op2("5",true), op3("6");

  std::vector<Answer> answers{op1, op2, op3};
  Question q1("How many questions are there?", answers);
  //q1.run();

  Question q2("What is the season in Sweden between December and March?", 
  {Answer("autumn"), Answer("spring"), Answer("winter", true), Answer("summer")});

  // q2.run();
  Question q3("Barack Obama was the US President in 2017",{Answer("true"), Answer("false", true)});

  // q3.run();

  // run all questions at once and then mark them
  std::vector<Question> questions{q1, q2, q3};

  int i = 1;
  for(auto &q: questions){
      std::cout << i << ". ";
      q.run();
      i++;
  }
}

Question.hpp

/**
* @file  : Question.hpp
* @author: blongho
* @since : 2018-11-25
* @brief : A class to hold an Question and its answers for use in a multiple choice exam
**/
#ifndef QUESTION_H
#define QUESTION_H
#include "Answer.hpp"
#include <vector>
#include <string>
#include <iostream>
#include <algorithm>    // std::random_shuffle
#include <exception>

class Question {
  private:
    std::string question;
    std::vector<Answer> options;

    void mark(const std::string &response)
    {
        std::cout << std::endl;
        if(response == correctAnswer()){
            std::cout << "Your choice, '" << response << "' is correct" << std::endl;
        }
        else
        {
            std::cout << "Your choice, '" << response << "' is wrong" << std::endl;
            int i = 1;
      
            for(auto &c: options){
                std::cout << i << ": ";
                c.printOn();
                i++;
            }
        }
        std::cout << std::endl;
    }

    std::string correctAnswer()
    {
        std::string answer;
        for(auto &ans: options){
            if(ans.isCorrect()){
                answer = ans.getValue();
                break;
            }
      }
      return answer;
    }
    
    void display(std::ostream &os=std::cout)
    {
        os << question << "\n";
        int i = 1;
       std::random_shuffle ( options.begin(), options.end());
        for(auto &ans: options){
            os << i << ": " ;
            ans.display();
            i++;
        }
        os << std::endl;
    }

  public:
    Question(){};
    Question(const std::string &q, const std::vector<Answer> &answers)
    :question(q), options(answers){}

    void setQuestion(const std::string &quest){
       question = quest;
    }
    void setOptions(const std::vector<Answer> &answers){
      options = answers;
    }

    std::vector<Answer> getOptions() const{
      return options;
    }
    std::string getQuestion() const{
      return question;
    }

   void run()
   {
        int intResponse{0};

        display(); // show the question and options

        // get valid response
        do{    
            std::string response;
            std::cout << "Your choice: ";
            std::getline(std::cin, response);

            try{
                intResponse = stoi(response);
            }catch(std::exception &e){
                std::cout << "Bad value entered for response [" << response << "]" << std::endl;
            }
            if( intResponse > options.size() ||  intResponse < 0){
                std::cout << "Your answer should be integer between 1 and " 
                << options.size() << std::endl;
            }
          
       }while(intResponse < 1 || intResponse > options.size());

        // still do control before accessing values in the vector
       if( intResponse <= options.size() &&  intResponse >0){
            std::string choice = options[ intResponse-1].getValue();

            mark(choice); // constrol and print response

        }else{
        std::cout << "Your answer should be integer between 1 and " << options.size()
          << std::endl;
       }
   }
};

#endif

This is an attempt to solve Linking questions to numbers from cplusplus.com forum