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drand48_r(3) — Linux manual page

drand48_r(3)             Library Functions Manualdrand48_r(3)

NAME        top

       drand48_r, erand48_r, lrand48_r, nrand48_r, mrand48_r, jrand48_r,       srand48_r, seed48_r, lcong48_r - generate uniformly distributed       pseudo-random numbers reentrantly

LIBRARY        top

       Standard C library (libc,-lc)

SYNOPSIS        top

#include <stdlib.h>int drand48_r(struct drand48_data *restrictbuffer,double *restrictresult);int erand48_r(unsigned shortxsubi[3],struct drand48_data *restrictbuffer,double *restrictresult);int lrand48_r(struct drand48_data *restrictbuffer,long *restrictresult);int nrand48_r(unsigned shortxsubi[3],struct drand48_data *restrictbuffer,long *restrictresult);int mrand48_r(struct drand48_data *restrictbuffer,long *restrictresult);int jrand48_r(unsigned shortxsubi[3],struct drand48_data *restrictbuffer,long *restrictresult);int srand48_r(long intseedval, struct drand48_data *buffer);int seed48_r(unsigned shortseed16v[3], struct drand48_data *buffer);int lcong48_r(unsigned shortparam[7], struct drand48_data *buffer);   Feature Test Macro Requirements for glibc (seefeature_test_macros(7)):       All functions shown above:           /* glibc >= 2.19: */ _DEFAULT_SOURCE               || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE

DESCRIPTION        top

       These functions are the reentrant analogs of the functions       described indrand48(3).  Instead of modifying the global random       generator state, they use the supplied databuffer.       Before the first use, this struct must be initialized, for       example, by filling it with zeros, or by calling one of the       functionssrand48_r(),seed48_r(), orlcong48_r().

RETURN VALUE        top

       The return value is 0.

ATTRIBUTES        top

       For an explanation of the terms used in this section, seeattributes(7).       ┌──────────────────────────┬───────────────┬─────────────────────┐       │Interface│Attribute│Value│       ├──────────────────────────┼───────────────┼─────────────────────┤       │drand48_r(),             │ Thread safety │ MT-Safe race:buffer │       │erand48_r(),             │               │                     │       │lrand48_r(),             │               │                     │       │nrand48_r(),             │               │                     │       │mrand48_r(),             │               │                     │       │jrand48_r(),             │               │                     │       │srand48_r(),seed48_r(), │               │                     │       │lcong48_r()              │               │                     │       └──────────────────────────┴───────────────┴─────────────────────┘

STANDARDS        top

       GNU.

SEE ALSO        top

drand48(3),rand(3),random(3)

COLOPHON        top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-05-17drand48_r(3)

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