PHP Manual: Sets the RNG seed

Description

void gmp_random_seed(GMPintstring $seed)

Parameters

seed

The seed to be set for the gmp_random, gmp_random_bits, and gmp_random_range functions.

A GMP object, an int, or a string that can be interpreted as a number following the same logic as if the string was used in gmp_init with automatic base detection (i.e. when base is equal to 0).

Return Values

No value is returned.

Errors/Exceptions

Throws a ValueError if seed is invalid.

Changelog

Version	Description
8.0.0	If `seed` is invalid, gmp_random_seed now throws a ValueError. Previously it emitted an `E_WARNING` and returned `false`.

Examples

Example #1 gmp_random_seed example

<?php
// set the seed
gmp_random_seed(100);

var_dump(gmp_strval(gmp_random(1)));

// set the seed to something else
gmp_random_seed(gmp_init(-100));

var_dump(gmp_strval(gmp_random_bits(10)));

// set the seed to something invalid
var_dump(gmp_random_seed('not a number'));

The above example will output:

string(20) "15370156633245019617"
string(3) "683"

Warning: gmp_random_seed(): Unable to convert variable to GMP - string is not an integer in %s on line %d
bool(false)

gmp_random_seed