Fastest way to generate a random boolean

c# performance random boolean
timedt picture timedt · Oct 4, 2013 · Viewed 66.1k times · Source

So there is several ways of creating a random bool in C#:

  • Using Random.Next(): rand.Next(2) == 0
  • Using Random.NextDouble(): rand.NextDouble() > 0.5

Is there really a difference? If so, which one actually has the better performance? Or is there another way I did not see, that might be even faster?

Answer

Aviran Cohen picture Aviran Cohen · Oct 4, 2013

The first option - rand.Next(2) executes behind the scenes the following code:

if (maxValue < 0)
{
    throw new ArgumentOutOfRangeException("maxValue",
        Environment.GetResourceString("ArgumentOutOfRange_MustBePositive", new object[] { "maxValue" }));
}
return (int) (this.Sample() * maxValue);

and for the second option - rand.NextDouble():

return this.Sample();

Since the first option contains maxValue validation, multiplication and casting, the second option is probably faster.

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