CODEWITHSUNDEEP
c++visual-c++
gn66
gn66

Reputation: 853

rand() and srand() function opengl visual cpp

I'me making a Pacman game in opengl and I need to generate 2 diferent numbers 0 or 1, that are responsable for the direction of my pacman deppending on the direction he's taking.

How can I generate a number with rand() function that generates 75% of randomness for one number and 25% of randomness for the other?

If I make:

n = rand() % 3;

It will get 2 different numbers. The problem is the percent of randomness I don't know how to make. I can make it with a cicle and a counter. But I was told I could do It directly in the rand() function. I search but I couldnt find nothing concrete on google.

Upvotes: 0

Views: 3067

Answers (3)

bames53
bames53

Reputation: 88155

Use the <random> library. The bernoulli_distribution will generate true with a given probability p, and false with probability 1-p.

#include <random>

#include <iostream>
#include <algorithm>
#include <iterator>

int main() {
    std::generate_n(std::ostream_iterator<bool>(std::cout," "), 10,
                    std::bind(std::bernoulli_distribution(0.25), std::mt19937()));
}

prints:

1 0 0 1 0 0 1 0 0 0

Upvotes: 3

lupz
lupz

Reputation: 3638

You can always go with a equally distributed random range from a to b and check your condition on the value like this:

if((rand() % 100)>=75)
    // 25%
    ;
else
    // 75 %
    ;

Upvotes: 2

Martin Beckett
Martin Beckett

Reputation: 96109

rand() gives you a random number between 0 and RAND_MAX (typical 32k)

So half the values will be between 0 and RAND_MAX/2, 1/3 will be between 0 and RAND_MAX/3 and 2/3 will be between RAND_MAX/3 and RAND_MAX.

Is that enough of a hint?

Upvotes: 2

Related Questions