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3. Library calls (functions within program libraries)

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LROUND

Section: Linux Programmer's Manual (3)
Updated: 2020-11-01
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NAME

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

SYNOPSIS

#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 feature_test_macros(7)):

All functions shown above:

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
 

DESCRIPTION

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

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 unspecified.  

ERRORS

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 large
An invalid floating-point exception (FE_INVALID) is raised.

These functions do not set errno.  

VERSIONS

These functions first appeared in glibc in version 2.1.  

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
lround(), lroundf(), lroundl(),
llround(), llroundf(), llroundl()
Thread safetyMT-Safe
 

CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008.  

SEE ALSO

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

COLOPHON

This page is part of release 5.10 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 https://www.kernel.org/doc/man-pages/.


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
VERSIONS
ATTRIBUTES
CONFORMING TO
SEE ALSO
COLOPHON

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