C++ Source Code /Tutorial für Anfänger

#include <iostream>
#include <ctime>

int main()
{
	unsigned long int guess, number, error, tries;
	char answer;
	srand((unsigned)time(0));
		
		do
		{

			tries = 1;
			number = rand();
			std::cout << "I think of a number between 0 and "<< RAND_MAX << ". Guess it!";
			std::cout << "\nFirst Guess: ";
			std::cin >> guess;
			if(guess == 19910801)
			{
				std::cout << "\n" << number << "\nCheater!";
				guess = number;
			}
			do
			{
				if (guess > number)
				{
					tries++;
					std::cout << "The number is smaller!\n";
					std::cout << "Guess #" << tries << ":";
					std::cin >> guess;
				}
				else
				{
					if(guess < number)
					{
					tries++;
					std::cout << "The number is bigger!\n";
					std::cout << "Guess #" << tries << ":";
					std::cin >> guess;
					}
				}
			}while(guess != number);
			std::cout << "\nCongratulations! You won!\nNumber of tries: " << tries;
			do
			{
				std::cout << "\nDo you want to play again?(y/n) ";
				std::cin >> answer;
				
				if (answer != 'n' && answer != 'N' && answer != 'y' && answer != 'y')
				{
					std::cout << "Error! Please reply only with 'y' or 'n'!\n(Help: y means yes, n means no)";
					error = 1;
				}
				else
				{
					error = 0;
				}
			}while(error == 1);
		}while(answer == 'y' || answer == 'Y');

	return 0;
}