You didn't specify a language, so here it is in C++.
#include <iostream>
#include <ctime>
int main()
{
srand(time(NULL));
int random, guess;
random = rand() % 100 + 1;
std::cout << "Random number generated!\nGuess the number: ";
std::cin >> guess;
if (guess == random)
std::cout << "Yes!";
else
std::cout << "No!";
return 0;
}