Program c++. Funkcja void push_back

#include <iostream>
#include <string>
#include <vector>
using namespace std;

char guess;
int total;

class Question {
public:
    void setValues( string, string, string, string, string, string, char, int );
    void askQuestion();
   
private:
    string Question_Text;
    string answer_1;
    string answer_2;
    string answer_3;
    string answer_4;
    string answer_5;
    char correct_answer;
    int Question_Score;
};

int main()
{
    int R;
    int load;
    string respond;
    cout << "Are you ready to start the quiz? Yes/No.\n";
    cin >> respond;
   
    if( respond == "Yes" || respond == "yes" ) {
        cout << "\n";
        cout << "Good luck!\n";
        cout << "\n";
        cout << "Press enter to continue.";
        cin.get();
        cin.ignore();
    } else {
        cout << "\n";
        cout << "Goodbye!\n";
        cin.ignore();
        cin.get();
        return 0;
    }
    Question q1;
    Question q2;
    Question q3;
    Question q4;
    Question q5;
    Question q6;
    Question q7;
    Question q8;
    Question q9;
    Question q10;
   
   
    q1.setValues( "1. Will i pass an exam?",
    "Yes",
    "Yes of course",
    "Absolutely yes",
    "Without any problems",
    "For sure",
    'c',
    5 );
   
    q2.setValues( "2. What is the highest place on Earth?",
    "Mount Rainier",
    "Mount Everest",
    "Mount Kinabalu",
    "Mount Damavand",
    "Nanga Parbat",
    'b',
    5 );
   
    q3.setValues( "3. Which of the planets is closest to the Sun?",
    "Jupiter",
    "Venus",
    "Saturn",
    "Mercury",
    "Neptune",
    'd',
    5 );
   
    q4.setValues( "4. When did the Second World War end?",
    "1944",
    "1945",
    "1942",
    "1943",
    "1946",
    'b',
    5 );
   
    q5.setValues( "5. Where is the tallest peak in Europe?",
    "France",
    "Italy",
    "Spain",
    "Austria",
    "Russia",
    'e',
    5 );
   
    q6.setValues( "6. What is the most spoken Language in the World?",
    "English",
    "Spanish",
    "Chinese",
    "Hindi",
    "Arabic",
    'c',
    5 );
   
    q7.setValues( "7. What is the poorest country in the world?",
    "Central African Republic",
    "Burundi",
    "Liberia",
    "Niger",
    "Mozambique",
    'a',
    5 );
   
    q8.setValues( "8. What is the richest country in the world",
    "Luxembourg",
    "Kuwait",
    "Qatar",
    "Ireland",
    "Norway",
    'c',
    5 );
   
    q9.setValues( "9. Who have largest army in the world?",
    "China",
    "United States",
    "Russia",
    "North Korea",
    "India",
    'a',
    5 );
   
    q10.setValues( "10. Where is the hottest place on Earth?",
    "Arabian Desert",
    "Sahara",
    "Gobi Desert",
    "Kalahari Desert",
    "Death Valley",
    'e',
    5 );
   
    vector < Question > questions = { q1, q2, q3, q4, q5, q6, q7, q8, q9, q10 };
    cout << "Which question do you want to load?";
    cin >> load;
    questions[ load - 1 ].askQuestion();
   
    /*q1.askQuestion();
        q2.askQuestion();
        q3.askQuestion();
        q4.askQuestion();
        q5.askQuestion();
        q6.askQuestion();
        q7.askQuestion();
        q8.askQuestion();
        q9.askQuestion();
        q10.askQuestion();*/
   
   
    cout << "Your Total Score is " << total << " out of 50!\n";
    cout << "\n";
   
    if( total > 25 ) {
        cout << R << "You pass" << "\n";
        cout << "\n";
        cin.get();
        cin.ignore();
        return 0;
    }
    else
    {
        cout << "You failed... Sorry, better luck next time.\n";
        cout << "\n";
    }
    cin.get();
    cin.ignore();
    return 0;
}

void Question::setValues( string q, string a1, string a2, string a3, string a4, string a5, char ca, int pa )
{
    Question_Text = q;
    answer_1 = a1;
    answer_2 = a2;
    answer_3 = a3;
    answer_4 = a4;
    answer_5 = a5;
    correct_answer = ca;
    Question_Score = pa;
}

void Question::askQuestion()
{
    cout << "\n";
    cout << Question_Text << "\n";
    cout << "a. " << answer_1 << "\n";
    cout << "b. " << answer_2 << "\n";
    cout << "c. " << answer_3 << "\n";
    cout << "d. " << answer_4 << "\n";
    cout << "e. " << answer_5 << "\n";
    cout << "\n";
   
    cout << "What is your answer?" << "\n";
    cin >> guess;
    if( guess == correct_answer ) {
        cout << "\n";
        cout << "Correct!" << "\n";
        total = total + Question_Score;
        cout << "\n";
        cout << "Press enter to continue." << "\n";
        cin.get();
        cin.ignore();
    }
    else
    {
        cout << "\n";
        cout << "Sorry, you're wrong..." << "\n";
        cout << "The correct answer is " << correct_answer << "." << "\n";
        cout << "\n";
        cout << "Press enter to continue." << "\n";
        cin.get();
        cin.ignore();
    }
}