Generate either 0 or 1 and not in between

Question

int random(){
    double x = ((double) rand() / (RAND_MAX)); // this i tried but only 0
    return x;
} 

how I generate either 0 or 1 randomly for a tic tac toe player to play

Answer 1

If you have C++11 you can use the new standard <random> library. In particular the std::bernoulli_distribution distribution gives true or false results (default convertible to 1 and 0 respectively).

// returns true or false
bool randomly_true(double p = 0.5)
{
    thread_local static std::mt19937 mt{std::random_device{}()};
    thread_local static std::bernoulli_distribution d;
    return d(mt, std::bernoulli_distribution::param_type{p});
}

int main()
{
    for(int i = 0; i < 30; ++i)
        std::cout << randomly_true() << '\n';
}

Output: (sample)

0
0
0
1
0
1
1
1
0
1

If you always want 1 or 0 integer values rather than true or false bool values you can force the conversion by returning int from the function:

// returns 1 or 0
int randomly_true(double p = 0.5)
{
    thread_local static std::mt19937 mt{std::random_device{}()};
    thread_local static std::bernoulli_distribution d;
    return d(mt, std::bernoulli_distribution::param_type{p});
}

Note: You should use this library in preference to rand() as there is no guarantee of quality with rand() and may be very poorly implemented.