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lround(3) — Linux manual page

lround(3)                Library Functions Manuallround(3)

NAME        top

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

LIBRARY        top

       Math library (libm,-lm)

SYNOPSIS        top

#include <math.h>long lround(doublex);long lroundf(floatx);long lroundl(long doublex);long long llround(doublex);long long llroundf(floatx);long long llroundl(long doublex);   Feature Test Macro Requirements for glibc (seefeature_test_macros(7)):       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 (seefenv(3)).       Note that unlike theround(3) andceil(3), functions, the return       type of these functions differs from that of their arguments.

RETURN VALUE        top

       These functions return the rounded integer value.       Ifx is a NaN or an infinity, or the rounded value is too large to       be stored in along (long long in the case of thell*functions),       then a domain error occurs, and the return value is unspecified.

ERRORS        top

       Seemath_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       large              An invalid floating-point exception (FE_INVALID) is raised.       These functions do not seterrno.

ATTRIBUTES        top

       For an explanation of the terms used in this section, seeattributes(7).       ┌──────────────────────────────────────┬───────────────┬─────────┐       │Interface│Attribute│Value│       ├──────────────────────────────────────┼───────────────┼─────────┤       │lround(),lroundf(),lroundl(),      │ Thread safety │ MT-Safe │       │llround(),llroundf(),llroundl()    │               │         │       └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS        top

       C11, POSIX.1-2008.

HISTORY        top

       glibc 2.1.  C99, POSIX.1-2001.

SEE ALSO        top

ceil(3),floor(3),lrint(3),nearbyint(3),rint(3),round(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            2025-05-17lround(3)

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

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