lround(3) — Linux manual page


LROUND(3)               Linux Programmer's Manual              LROUND(3)

NAME         top

       lround, lroundf, lroundl, llround, llroundf, llroundl - round to
       nearest integer

SYNOPSIS         top

       #include <math.h>

       long lround(double x);
       long lroundf(float x);
       long lroundl(long double x);

       long long llround(double x);
       long long llroundf(float x);
       long long llroundl(long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see

       All functions shown above:
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

DESCRIPTION         top

       These functions round their argument to the nearest integer
       value, rounding halfway cases away from zero, regardless of the
       current rounding direction (see fenv(3)).

       Note that unlike the round(3) and ceil(3), functions, the return
       type of these functions differs from that of their arguments.

RETURN VALUE         top

       These functions return the rounded integer value.

       If x is a NaN or an infinity, or the rounded value is too large
       to be stored in a long (long long in the case of the ll*
       functions), then a domain error occurs, and the return value is

ERRORS         top

       See math_error(7) for information on how to determine whether an
       error has occurred when calling these functions.

       The following errors can occur:

       Domain error: x is a NaN or infinite, or the rounded value is too
              An invalid floating-point exception (FE_INVALID) is

       These functions do not set errno.

VERSIONS         top

       These functions first appeared in glibc in version 2.1.

ATTRIBUTES         top

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

       │Interface                             Attribute     Value   │
       │lround(), lroundf(), lroundl(),       │ Thread safety │ MT-Safe │
       │llround(), llroundf(), llroundl()     │               │         │

CONFORMING TO         top

       C99, POSIX.1-2001, POSIX.1-2008.

SEE ALSO         top

       ceil(3), floor(3), lrint(3), nearbyint(3), rint(3), round(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

                               2021-03-22                      LROUND(3)

Pages that refer to this page: lrint(3)round(3)