PHP | gmp_random_seed() Function

The gmp_random_seed() is an inbuilt function in PHP which sets the RNG seed( Random Number Generation).

Syntax:

void gmp_random_seed ( mixed $seed )

Parameters: The gmp_random_seed() function accepts a single parameter as mentioned above and explained below:

• $seed: It is the only parameter required by the gmp_random_seed() function which is to be set for gmp_random(), gmp_random_range() and gmp_random_bits() functions. This parameter can be a GMP resource in PHP 5.5 or earlier, a GMP object in PHP version 5.6 and later, or also allowed to pass a numeric string provided that it is possible to convert that string to a number.

Return Value: The gmp_random_seed() function returns NULL on success and returns FALSE on failure.

Note:

Warning: The function generates an E-Warning and returns False if the seed is not valid.

Examples: Below programs illustrate the gmp_random_seed() function in PHP:

Program 1:

<?php

// PHP code implementing the gmp_random_seed function

// setting the seed
gmp_random_seed(100);

var_dump(gmp_strval(gmp_random(1)));

?>

Output:

string(19) "7842303329126688544"

Program 2:

<?php
//php code implementing the gmp_random_seed() function

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

var_dump(gmp_strval(gmp_random_bits(10)));

?>

Output:

string(3) "800"

Program 3:

<?php
//PHP code implementing gmp_random_seed() function

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

?>

Output:

gmp_random_seed(): Unable to convert variable to GMP - string is not an integer -- at line 5
bool(false)

Reference: http://php.net/manual/en/function.gmp-random-seed.php