mt_srand(3) [php man page]

MT_SRAND(3)								 1							       MT_SRAND(3)

mt_srand - Seed the better random number generator

SYNOPSIS

       void mt_srand ([int  $seed])

DESCRIPTION

	Seeds the random number generator with $seed or with a random value if no $seed is given.

       Note

	      There is no need to seed the random number generator with srand(3) or mt_srand(3) as this is done automatically.

PARAMETERS

	      o $seed
		- An optional seed value

RETURN VALUES

	No value is returned.

CHANGELOG

       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.2.1	|						    |
       |	|						    |
       |	|  The	Mersenne  Twister implementation in PHP now |
       |	| uses a new seeding algorithm by  Richard  Wagner. |
       |	| Identical   seeds  no  longer  produce  the  same |
       |	| sequence of values they did in previous versions. |
       |	| This	behavior  is  not expected to change again, |
       |	| but it is considered unsafe to rely upon it none- |
       |	| theless.					    |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES

       Example #1

	      mt_srand(3) example

	      <?php
	      // seed with microseconds
	      function make_seed()
	      {
		list($usec, $sec) = explode(' ', microtime());
		return (float) $sec + ((float) $usec * 100000);
	      }
	      mt_srand(make_seed());
	      $randval = mt_rand();
	      ?>

SEE ALSO

       mt_rand(3), mt_getrandmax(3), srand(3).

PHP Documentation Group 													       MT_SRAND(3)

MT_RAND(3)								 1								MT_RAND(3)

mt_rand - Generate a better random value

SYNOPSIS

       int mt_rand (void  )

DESCRIPTION

       int mt_rand (int  $min, int  $max)

	Many  random  number  generators of older libcs have dubious or unknown characteristics and are slow. By default, PHP uses the libc random
       number generator with the rand(3) function. The mt_rand(3) function is a drop-in replacement for this. 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.

	If called without the optional $min, $max arguments mt_rand(3) returns a pseudo-random value between 0 and mt_getrandmax(3). If you want a
       random number between 5 and 15 (inclusive), for example, use mt_rand(5, 15).

       Caution

	      This  function  does  not generate cryptographically secure values, and should not be used for cryptographic purposes. If you need a
	      cryptographically secure value, consider using random_int(3), random_bytes(3), or openssl_random_pseudo_bytes(3) instead.

PARAMETERS

	      o $min
		- Optional lowest value to be returned (default: 0)

	      o $max
		- Optional highest value to be returned (default: mt_getrandmax(3))

RETURN VALUES

	A random integer value between $min (or 0) and $max (or mt_getrandmax(3), inclusive), or FALSE if $max is less than $min.

CHANGELOG

       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.3.4	|						    |
       |	|						    |
       |	|  Issues an E_WARNING and returns FALSE if $max  < |
       |	| $min. 					    |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES

       Example #1

	      mt_rand(3) example

	      <?php
	      echo mt_rand() . "
";
	      echo mt_rand() . "
";

	      echo mt_rand(5, 15);
	      ?>

	      The above example will output something similar to:

	      1604716014
	      1478613278
	      6

NOTES

       Caution

	       The  distribution of mt_rand(3) return values is biased towards even numbers on 64-bit builds of PHP when $max is beyond 2^32. This
	      is because if $max is greater than the value returned by mt_getrandmax(3), the output of the random number generator must be  scaled
	      up.

SEE ALSO

       mt_srand(3), mt_getrandmax(3), random_int(3), random_bytes(3), openssl_random_pseudo_bytes(3), rand(3).

PHP Documentation Group 														MT_RAND(3)