header file

functions.h

#pragma once
#include <iostream>
#include <string>

using int32 = int;

struct Info
{
	const int32 numberOfTries = 5;
	const int32 isoLength = 5;//variable to store isogram length
	std::string userGuess = "";//store the guess in string
};

std::string getGuess(std::string guess, int32 wordLength)
{
	while (guess.length() != wordLength)
	{
		std::cout << "enter a valid guess: " << std::flush;
		std::getline(std::cin, guess);//get a guess from the player
	}
	return guess;
}

//introduce the game
void printGame()
{
	std::cout << "Welcome to Bulls & Cows" << std::endl;
	std::cout << "In this game you guess the isogram" << std::endl;
	std::cout << "Would you like to play?" << std::endl;
}

//prints the guess back to the player
void printGuess(std::string guess)
{
	std::cout << guess + "\n" << std::endl;
}

//the loop for game
void playGame(Info data)
{
	for (int32 currentTry = 0; currentTry < data.numberOfTries; currentTry++)
	{
		printGuess(getGuess(data.userGuess, data.isoLength));
	}
}

//asks whether to play game or not
bool isInGame(Info data)
{
	std::cout << "Press 'y' or 'Y' to play" << std::endl;
	std::getline(std::cin, data.userGuess);
	return (data.userGuess[0] == 'y') || (data.userGuess[0] == 'Y');
}

void gameOver()
{
	std::cout << "thank you for playing\n" << std::endl;
}

main.cpp

#include "functions.h"

//application entry point
int main()
{
	Info data;
	printGame();//introduce game
	while (isInGame(data))
	{
		std::cout << std::endl;
		playGame(data);
		gameOver();
	}
	return 0;
}