rand(3)

NAME

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

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <stdlib.h>
void
srand(unsigned seed);
void
sranddev(void);
int
rand(void);
int
rand_r(unsigned *ctx);

DESCRIPTION

These interfaces are obsoleted by random(3).

The rand() function computes a sequence of pseudo-random in

tegers in the
range of 0 to RAND_MAX (as defined by the header file

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 automatical

ly seeded with
a value of 1.

The sranddev() function initializes a seed using the ran

dom(4) random
number device which returns good random numbers. However,

the rand()
function still remains unsuitable for cryptographic use.

The rand_r() function provides the same functionality as

rand(). A
pointer to the context value ctx 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 C89'').

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

#6 document.

BSD May 25, 1999

BSD