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/*
Copyright (c) 1990 Regents of the University of California.
All rights reserved.
*/
/*
FUNCTION
<<rand>>, <<srand>>---pseudo-random numbers
INDEX
rand
INDEX
srand
INDEX
rand_r
SYNOPSIS
#include <stdlib.h>
int rand(void);
void srand(unsigned int <[seed]>);
int rand_r(unsigned int *<[seed]>);
DESCRIPTION
<<rand>> returns a different integer each time it is called; each
integer is chosen by an algorithm designed to be unpredictable, so
that you can use <<rand>> when you require a random number.
The algorithm depends on a static variable called the ``random seed'';
starting with a given value of the random seed always produces the
same sequence of numbers in successive calls to <<rand>>.
You can set the random seed using <<srand>>; it does nothing beyond
storing its argument in the static variable used by <<rand>>. You can
exploit this to make the pseudo-random sequence less predictable, if
you wish, by using some other unpredictable value (often the least
significant parts of a time-varying value) as the random seed before
beginning a sequence of calls to <<rand>>; or, if you wish to ensure
(for example, while debugging) that successive runs of your program
use the same ``random'' numbers, you can use <<srand>> to set the same
random seed at the outset.
RETURNS
<<rand>> returns the next pseudo-random integer in sequence; it is a
number between <<0>> and <<RAND_MAX>> (inclusive).
<<srand>> does not return a result.
NOTES
<<rand>> and <<srand>> are unsafe for multi-threaded applications.
<<rand_r>> is thread-safe and should be used instead.
PORTABILITY
<<rand>> is required by ANSI, but the algorithm for pseudo-random
number generation is not specified; therefore, even if you use
the same random seed, you cannot expect the same sequence of results
on two different systems.
<<rand>> requires no supporting OS subroutines.
*/
#define _DEFAULT_SOURCE
#include <stdlib.h>
int
rand(void)
{
return (int)(random() & RAND_MAX);
}