Separate two inputs C++ - c++

Question

I have made a quiz helper, but, as I want it for you to be able to input a new question without starting it, I made a do/while loop. The first run goes fine. When it asks you if you want to input another question, if you choose y, it runs the main program too at the same time, and the program registers y as a question. How do I separate this?Code:
#include <cctype>
#include <iostream>
#include <string>
#include "Quiz.h"
#include "Quiz2.h"
char choice;
int main()
{
do{
quiz();
std::cout << "Da li zelite da vam odgovorim na jos jedno pitanje?(y/n)" << std::endl;
std::cin >> choice;
} while(choice != 'n');
}
The first header file just includes the function to find words:
#ifndef QUIZ_H_INCLUDED
#define QUIZ_H_INCLUDED
bool contains_word(const std::string& sentence, const std::string& word)
{
size_t pos = 0;
while ((pos = sentence.substr(pos).find(word)) != std::string::npos) {
if (!(isalpha(sentence[pos - 1])) || !(isalpha(sentence[pos + word.size() + 1])))
return true;
}
return false;
}
#endif
And the other one contains the real code, it is partially in Serbian:
#ifndef QUIZ2_H_INCLUDED
#define QUIZ2_H_INCLUDED
int quiz()
{
std::string sentence;
std::cout << "Ukucajte pitanje ili kljucne reci: " << std::flush;
std::getline(std::cin, sentence);
std::string word ("Belgija");
std::string word2 ("regija");
std::string word3 ("Kanada");
std::string word4 ("teritorija");
std::string word5 ("Holandija");
std::string word6 ("delova");
if (contains_word(sentence, word) && contains_word(sentence, word2))
std::cout << "Odgovor je 3 regije." << std::endl;
else if (contains_word(sentence, word3) && contains_word(sentence, word4))
std::cout << "Odgovor je 3 teritorije." << std::endl;
else if (contains_word(sentence, word5) && contains_word(sentence, word6))
std::cout << "Odgovor je 3 dela." << std::endl;
else
std::cout << "Nisam mogao pronaci odgovor na to pitanje!" << std::endl;
return 0;
}
#endif
Any help is appreciated.

Answer 1

There is a newline character after a choice, so just add cin.ignore:
std::cin >> choice;
std::cin.ignore();
It ignores one character from input.
Alternative solution
Alternatively, you could discard all empty lines in quiz() function - substitute
std::getline(std::cin, sentence);
with
do {
std::getline(std::cin, sentence);
} while( sentence.empty() );
Other issue with the code
The contains_word function should be corrected. You shouldn't get value of sentence[pos + word.size() + 1] if it is possible for the word to be at the very end of sentence (subscript past the end of array).
Similar error in sentence[pos - 1] - what if pos is 0? You get some random stuff before the string.
You have to rework the condition also - certainly if( !(...) || !(...) ) is not what you wanted.
Should be something like this:
bool contains_word(const std::string& sentence, const std::string& word)
{
size_t pos = 0;
while ((pos = sentence.substr(pos).find(word)) != std::string::npos) {
if( (pos == 0 || isalpha(sentence[pos - 1])) &&
(pos + word.size() == sentence.size() || isalpha(sentence[pos + word.size()])) )
return true;
}
return false;
}

Answer 2

getline() and cin don't play well together. After a cin operation there is typically a newline left in the input stream that the getline reads and immediately concludes it is done. You can "solve" the problem by calling getline twice and ignoring the first result. However note that this only happens AFTER a call to cin, so the first time thru you should NOT use getline twice. This is why I say they "don't play well together".