// Example program
#include <algorithm>
#include <string>
#include <vector>
#include <iostream>
int main()
{
const std::vector<std::string> days = {
"mo", "tu", "we", "th", "fr", "sa", "su"
};
bool found = false;
while (found == false) {
char dayOne, dayTwo;
std::cout << "Please enter the first letter of the day" << std::endl;
std::cin >> dayOne;
std::cout << "Please enter the second letter of the day" << std::endl;
std::cin >> dayTwo;
std::string fullDay;
fullDay += std::tolower(dayOne);
fullDay += std::tolower(dayTwo);
found = std::find(days.begin(), days.end(), fullDay) != days.end();
std::cout << (found ? "correct day " : "invalid day, please try again ")
<< fullDay
<< std::endl;
}
}