Random\Engine\Xoshiro256StarStar::__construct

(PHP 8 >= 8.2.0)

Random\Engine\Xoshiro256StarStar::__construct — Constructs a new xoshiro256** engine

Description

public function Random\Engine\Xoshiro256StarStar::__construct(string|int|null $seed = null)

Parameters

seed

How the internal 256 bit (32 byte) state consisting of four unsigned 64 bit integers is seeded depends on the type used as the seed.

Type	Description
null	Fills the state with 32 random bytes generated using the CSPRNG.
int	Fills the state with four consecutive values generated with the SplitMix64 algorithm that was seeded with `seed` interpreted as an unsigned 64 bit integer.
string	Fills the state by interpreting a 32 byte string as four little-endian unsigned 64 bit integers.

Errors/Exceptions

If the length of a string seed is not 32 bytes, a ValueError will be thrown.
If a string seed consists of 32 NUL bytes ("\x00"), a ValueError will be thrown.

Examples

Example #1 Random\Engine\Xoshiro256StarStar::__construct() example

<?php
// Uses a random 256 Bit seed.
$e = new \Random\Engine\Xoshiro256StarStar();

$r = new \Random\Randomizer($e);
?>

Example #2 Deriving a seed from a string

<?php
$string = "My string seed";

// Hash the string with SHA-256 using binary output to turn the
// $string into a 256 Bit seed. Using the same string will result
// in the same sequence of randomness.
$e = new \Random\Engine\Xoshiro256StarStar(
    hash('sha256', $string, binary: true)
);

echo bin2hex($e->generate()), "\n";
?>

The above example will output:

6e013453678388c2