Ambiguous errors when trying to compile C++ code - c++

Question

When trying to compile the code below I get three errors.
'iterator_category': is not a member of any direct or indirect base class of 'std::iterator_traits<_InIt>'
'_Iter_cat_t' : Failed to specialize alias template
type 'unknown-type' unexpected
I'm quite new to C++ and have gone over the code many times changing snippets but nothing helps. Any help deciphering these error messages is much appreciated.
#include "../../std_lib_facilities.h"
class Puzzle {
public:
vector<char> letters;
Puzzle(int my_size);
void generate(void);
void enter_letters(void);
void feedback(Puzzle puzzle);
private:
int size = 4;
};
Puzzle::Puzzle(int my_size)
{
size = my_size;
}
//Generate size unique letters for the letters array.
void Puzzle::generate(void)
{
for (int i = 0; i < size; ++i) {
char rand = randint(26) - 1 + 'a';
while ((find(letters[0], letters[size], rand) != letters[size])) {
rand = randint(26) - 1 + 'a';
}
letters[i] = rand;
}
}
//Let the user enter size unique letters.
void Puzzle::enter_letters(void)
{
cout << "Enter four different letters seperated by spaces:\n";
for (int i = 0; i < size; ++i) {
char letter;
cin >> letter;
letters[i] = letter;
}
}
//Tell the user how many bulls and cows they got.
void Puzzle::feedback(Puzzle puzzle)
{
int cows = 0, bulls = 0;
for (int i = 0; i < size; i++) { //input
for (int j = 0; j < size; ++j) { //puzzle
if (i == j && letters[i] == puzzle.letters[j]) {
++bulls;
break;
}
else if (letters[i] == puzzle.letters[j]) {
++cows;
break;
}
}
}
cout << "Bulls: " << bulls << "\nCows: " << cows << "\n";
}
//Seed the random function.
void seed(void)
{
int sum = 0;
cout << "Enter a random string of characters:\n";
string str;
cin >> str;
for (char& c : str)
sum += c;
srand(sum);
}
int main()
{
constexpr int GAME_SIZE = 4;
seed();
Puzzle puzzle(GAME_SIZE);
puzzle.generate();
Puzzle input(GAME_SIZE);
input.enter_letters();
while (puzzle.letters != input.letters) {
input.feedback(puzzle);
input.enter_letters();
}
cout << "Congragulations, you did it!\n";
keep_window_open();
return 0;
}

Answer 1

You're using find() wrong.
find(letters[0], letters[size], rand)
Your letters is a std::vector. You're passing the first value in the vector, and the last value in the vector, to std::find.
This is actually undefined behavior, since size is not always the actual size of your letters vector. So, you'll be getting a random crash, as an extra bonus here in addition to your compilation error.
The first two parameters to std::find are iterators of a sequence to search, and not values.
This should be:
find(letters.begin(), letters.end(), rand)
Also, your overall algorithm is broken. Once letters reaches a certain size, your random number generating code will take ... a significant time to find some new letter to add to letters, that's not used already. Once letters manages to acquire all 26 characters of the alphabet, this will turn into an infinite loop. But that would be a different question...