Constructs a new PCG Oneseq 128 XSL RR 64 engine

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- Random\Engine\PcgOneseq128XslRr64
- Constructs a new PCG Oneseq 128 XSL RR 64 engine

# Random\Engine\PcgOneseq128XslRr64::__construct

(PHP 8 >= 8.2.0)

Random\Engine\PcgOneseq128XslRr64::__construct — Constructs a new PCG Oneseq 128 XSL RR 64 engine

### Description

public Random\Engine\PcgOneseq128XslRr64::__construct(string|int|null `$seed` = `null`)

### Parameters

`seed`

  How the internal 128 bit (16 byte) state consisting of one unsigned 128 bit integer is seeded depends on the type used as the `seed`.

  Type | Description
  --- | ---
  null | Fills the state with 16 random bytes generated using the CSPRNG.
  int | Fills the state by setting the state to `0`, advancing the engine one step, adding the value of `seed` interpreted as an unsigned 64 bit integer, and advancing the engine another step.
  string | Fills the state by interpreting a 16 byte string as a little-endian unsigned 128 bit integer.

### Errors/Exceptions

- If the length of a string `seed` is not 16 bytes, a ValueError will be thrown.

### Examples

Example #1 Random\Engine\PcgOneseq128XslRr64::__construct() example

    <?php
    // Uses a random 128 Bit seed.
    $e = new \Random\Engine\PcgOneseq128XslRr64();

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

Example #2 Deriving a seed from a string

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

    // Hash the string with truncated SHA-256 using binary output
    // to turn the $string into a 128 Bit seed. Using the same
    // string will result in the same sequence of randomness.
    $e = new \Random\Engine\PcgOneseq128XslRr64(
        substr(hash('sha256', $string, binary: true), 0, 16)
    );

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

The above example will output:

    8333ef59315b16d8