Esercizio C++: Conteggio caratteri di una stringa in un'altra stringa

#include <iostream>
#include <string>

using namespace std;

unsigned int conteggio_caratteri(string source, string search_string) {
  auto found_chars_counter = 0;
  for(char search_char: search_string) {
    cout << "search_char: "<< search_char<< endl;
    auto pos = 0; //posizione da dove iniziare la ricerca
    while (pos != string::npos) {
      cout << "search from pos "<< pos<< endl;
      pos = source.find(search_char,pos+1);
      found_chars_counter++;
      cout << "found " << search_char << " at pos " << pos << endl;
    }
  }
  return found_chars_counter;
}


int main() {
  std::cout << conteggio_caratteri("Pinco Pallo","aeiuo") << endl;
  return 0;
}