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RANDOM_R
Section: Linux Programmer's Manual (3)
Updated: 2008-03-07
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NAME
random_r, srandom_r, initstate_r, setstate_r - reentrant
random number generator
SYNOPSIS
#include <stdlib.h>
int random_r(struct random_data *buf, int32_t *result);
int srandom_r(unsigned int seed, struct random_data *buf);
int initstate_r(unsigned int seed, char *statebuf,
size_t statelen, struct random_data *buf);
int setstate_r(char *statebuf, struct random_data *buf);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
random_r(),
srandom_r(),
initstate_r(),
setstate_r():
-
_SVID_SOURCE || _BSD_SOURCE
DESCRIPTION
These functions are the reentrant equivalents
of the functions described in
random(3).
They are suitable for use in multithreaded programs where each thread
needs to obtain an independent, reproducible sequence of random numbers.
The
random_r()
function is like
random(3),
except that instead of using state information maintained
in a global variable,
it uses the state information in the argument pointed to by
buf.
The generated random number is returned in the argument
result.
The
srandom_r()
function is like
srandom(3),
except that it initializes the seed for the random number generator
whose state is maintained in the object pointed to by
buf,
instead of the seed associated with the global state variable.
The
initstate_r()
function is like
initstate(3)
except that it initializes the state in the object pointed to by
buf,
rather than initializing the global state variable.
The
setstate_r()
function is like
setstate(3)
except that it modifies the state in the object pointer to by
buf,
rather than modifying the global state variable.
RETURN VALUE
All of these functions return 0 on success, or -1 on error.
ERRORS
- EINVAL
-
A state array of less than 8 bytes was specified to
initstate_r().
- EINVAL
-
The
statebuf
or
buf
argument to
setstate_r()
was NULL.
- EINVAL
-
The
buf
or
result
argument to
random_r()
was NULL.
CONFORMING TO
These functions are nonstandard glibc extensions.
SEE ALSO
drand48(3),
rand(3),
random(3)
COLOPHON
This page is part of release 3.27 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- CONFORMING TO
-
- SEE ALSO
-
- COLOPHON
-
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