lround(3) — Linux manual page


lround(3)               Library Functions Manual               lround(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(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);

   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.

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()   │               │         │

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 the man-pages (Linux kernel and C library
       user-space interface documentation) project.  Information about
       the project can be found at 
       ⟨⟩.  If you have a bug report
       for this manual page, see
       This page was obtained from the tarball man-pages-6.9.1.tar.gz
       fetched from
       ⟨⟩ on
       2024-06-26.  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 is not
       part of the original manual page), send a mail to

Linux man-pages 6.9.1          2024-05-02                      lround(3)

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