C++ Multiple choices

multiple_choice.cpp

#include <fstream>
#include <iostream>

using namespace std;

typedef struct Question {
  string text;
  string one;
  string two;
  string three;
  string four;
  string correct;
} Question;

void getQuestion(Question &question, const string filename,
                 const unsigned int qn) {
  fstream infile(filename.c_str(), ios::in);

  if (!infile)
    return;

  string dump;
  for (int i = 0; i < (qn * 6); i++)
    getline(infile, dump);

  getline(infile, question.text);
  getline(infile, question.one);
  getline(infile, question.two);
  getline(infile, question.three);
  getline(infile, question.four);
  getline(infile, question.correct);
}

int main() {
  const unsigned int QUESTION_COUNT = 20;
  const string INPUT_FILENAME = "questions.txt";

  srand(time(NULL));

  unsigned int score = 0;
  unsigned int questionArray[QUESTION_COUNT] = {0};

  Question question;

  for (int _ = 0; _ < QUESTION_COUNT; _++) {
    int qn = 0;
    while (true) {
      qn = rand() % QUESTION_COUNT;
      if (!questionArray[qn])
        break;
    }

    questionArray[qn] = qn;
    getQuestion(question, INPUT_FILENAME, questionArray[qn]);
    cout << question.text << endl
         << "1) " << question.one << endl
         << "2) " << question.two << endl
         << "3) " << question.three << endl
         << "4) " << question.four << endl;

    char response;
    cin >> response;

    if (response == question.correct[0])
      score++;
  }
  cout << "You got " << int((score / (double)QUESTION_COUNT) * 100)
       << "\% correct, " << score << "/" << QUESTION_COUNT << endl;
  return 0;
}

questions.txt

What is the capital of USA
Atlanta
Washington DC
New York
Chicago
2
What is the capital of United Kingdom
London
Scotland
Birmingham
Heathrow
1
What is the capital of New York
Syracuse
Albany
Buffalo
New York City
1
What is the capital of California
San Diego
San Francisco
Los Angeles
Sacramento
4
What is the capital of Canada
Toronto
Ottawa
Nova Scotia
Victoria
2
Where is Los Angeles
California
San Diego
Nevada
Utah
1
Where is Louisiana
Canada
France
USA
Mexico
3
What is capital of France
Berlin
Paris
Belgium
London
2
Which state is in the west coast
Utah
California
Illinois
New York
2
Which state is in East Coast
California
San Diego
New York
Nevada
3
Which state is biggest
California
Florida
Nevada
Utah
1
which state is smallest
California
Texas
Florida
Vermont
4
Which state in in EST
California
San Diego
Florida
Nevada
3
Which state is in PST
New York Diego
California
Illinois
Florida
2
Which Country is on the North of US
Canada
Mexico
Brazil
France
1
Which Country is in Asia
Canada
China
Brazil
France
2
Which Country is in Europe
Canada
China
Brazil
France
4
Which Country is in South America
Canada
China
Brazil
France
3
Which state is east of Mississippi River
Virginia
Colorado
Nevada
South Dakota
1
Which state is west of Mississippi River
Virginia
Florida
Nevada
Alabama
3