drand48_r(3) — Linux manual page


DRAND48_R(3)            Linux Programmer's Manual           DRAND48_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

SYNOPSIS         top

       #include <stdlib.h>

       int drand48_r(struct drand48_data *restrict buffer,
                     double *restrict result);
       int erand48_r(unsigned short xsubi[3],
                     struct drand48_data *restrict buffer,
                     double *restrict result);

       int lrand48_r(struct drand48_data *restrict buffer,
                     long *restrict result);
       int nrand48_r(unsigned short xsubi[3],
                     struct drand48_data *restrict buffer,
                     long *restrict result);

       int mrand48_r(struct drand48_data *restrict buffer,
                     long *restrict result);
       int jrand48_r(unsigned short xsubi[3],
                     struct drand48_data *restrict buffer,
                     long *restrict result);

       int srand48_r(long int seedval, struct drand48_data *buffer);
       int seed48_r(unsigned short seed16v[3], struct drand48_data *buffer);
       int lcong48_r(unsigned short param[7], struct drand48_data *buffer);

   Feature Test Macro Requirements for glibc (see

       All functions shown above:
           /* Glibc since 2.19: */ _DEFAULT_SOURCE
               || /* Glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE

DESCRIPTION         top

       These functions are the reentrant analogs of the functions
       described in drand48(3).  Instead of modifying the global random
       generator state, they use the supplied data buffer.

       Before the first use, this struct must be initialized, for
       example, by filling it with zeros, or by calling one of the
       functions srand48_r(), seed48_r(), or lcong48_r().

RETURN VALUE         top

       The return value is 0.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │Interface                 Attribute     Value               │
       │drand48_r(), erand48_r(), │ Thread safety │ MT-Safe race:buffer │
       │lrand48_r(), nrand48_r(), │               │                     │
       │mrand48_r(), jrand48_r(), │               │                     │
       │srand48_r(), seed48_r(),  │               │                     │
       │lcong48_r()               │               │                     │

CONFORMING TO         top

       These functions are GNU extensions and are not portable.

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.13 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at

GNU                            2021-03-22                   DRAND48_R(3)

Pages that refer to this page: rand(3)