Get random boolean true/false in PHP

72
votes

What would be the most elegant way to get a random boolean true/false in PHP?

I can think of:

$value = (bool)rand(0,1);

But does casting an integer to boolean bring any disadvantages?

Or is this an "official" way to do this?

4
phprandomboolean
mt_rand() is better than rand(), check this answer - HamZa
It's a one liner that does the exact task you need. What kind disadvantages do you have in mind? - Álvaro González
For readability I would recommend either rand(0,1) == 1 or rand(0,1) > 0. Implicit casting, although documented, is kind of hard to read imo. - Caramiriel
This is what I'd use: array_rand(array(True, False)). - Amal Murali
You don't need to explicitly cast to a bool if you only want 'truthiness'. 0 evaluates to falsy, 1 to truthy. - dteoh

4 Answers

135
votes

If you don't wish to have a boolean cast (not that there's anything wrong with that) you can easily make it a boolean like this:

$value = rand(0,1) == 1;

Basically, if the random value is 1, yield true, otherwise false. Of course, a value of 0 or 1 already acts as a boolean value; so this:

if (rand(0, 1)) { ... }

Is a perfectly valid condition and will work as expected.

Alternatively, you can use mt_rand() for the random number generation (it's an improvement over rand()). You could even go as far as openssl_random_pseudo_bytes() with this code:

$value = ord(openssl_random_pseudo_bytes(1)) >= 0x80;

Update

In PHP 7.0 you will be able to use random_int(), which generates cryptographically secure pseudo-random integers:

$value = (bool)random_int(0, 1);
8
votes

I use a simply

rand(0,1) < 0.5
2
votes

Just for completeness, if you want use it in an if condition, there is no need to cast, since 0 is considered false:

if (mt_rand(0,1)) {
  // whatever
}

Note: mt_rand is 4x faster than rand

The mt_rand() function is a drop-in replacement for the older rand(). It uses a random number generator with known characteristics using the "Mersenne Twister", which will produce random numbers four times faster than what the average libc rand() provides.

0
votes

php stan recomended

1 === random_int(0, 1)