lround(3) Library Functions Manual lround(3)
NAME
lround, lroundf, lroundl, llround, llroundf, llroundl - round to near-
est integer
LIBRARY
Math library (libm, -lm)
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);
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 round-
ing 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.
ATTRIBUTES
For an explanation of the terms used in this section, see attrib-
utes(7).
┌───────────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├───────────────────────────────────────────┼───────────────┼─────────┤
│ lround(), lroundf(), lroundl(), │ Thread safety │ MT-Safe │
│ llround(), llroundf(), llroundl() │ │ │
└───────────────────────────────────────────┴───────────────┴─────────┘
STANDARDS
C11, POSIX.1-2008.
HISTORY
glibc 2.1. C99, POSIX.1-2001.
SEE ALSO
ceil(3), floor(3), lrint(3), nearbyint(3), rint(3), round(3)
Linux man-pages 6.7 2023-10-31 lround(3)
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