srand(3) [php man page]

SRAND(3)								 1								  SRAND(3)

srand - Seed the random number generator

SYNOPSIS

       void srand ([int  $seed])

DESCRIPTION

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

       Note

	      As  of  PHP  4.2.0,  there is no need to seed the random number generator with srand(3) or mt_srand(3) as this is now done automati-
	      cally.

PARAMETERS

	      o $seed
		- Optional seed value

RETURN VALUES

	No value is returned.

CHANGELOG

       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 4.2.0	|						    |
       |	|						    |
       |	|  The $seed becomes optional  and  defaults  to  a |
       |	| random value if omitted.			    |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES

       Example #1

	      srand(3) example

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

SEE ALSO

       rand(3), getrandmax(3), mt_srand(3).

PHP Documentation Group 														  SRAND(3)

RAND(3) 						   BSD Library Functions Manual 						   RAND(3)

NAME

     rand, rand_r, srand, sranddev -- bad random number generator

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <stdlib.h>

     int
     rand(void);

     int
     rand_r(unsigned *seed);

     void
     srand(unsigned seed);

     void
     sranddev(void);

DESCRIPTION

     These interfaces are obsoleted by random(3).

     The rand() function computes a sequence of pseudo-random integers in the range of 0 to RAND_MAX (as defined by the header file <stdlib.h>).

     The srand() function sets its argument seed as the seed for a new sequence of pseudo-random numbers to be returned by rand().  These
     sequences are repeatable by calling srand() with the same seed value.

     If no seed value is provided, the functions are automatically seeded with a value of 1.

     The sranddev() function initializes a seed, using the random(4) random number device which returns good random numbers, suitable for crypto-
     graphic use.

     The rand_r() function provides the same functionality as rand().  A pointer to the context value seed must be supplied by the caller.

SEE ALSO

     random(3), random(4)

STANDARDS

     The rand() and srand() functions conform to ISO/IEC 9899:1990 (``ISO C90'').

     The rand_r() function is as proposed in the POSIX.4a Draft #6 document.

BSD
								   May 25, 1999 							       BSD