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man pages section 3: Extended Library Functions, Volume 2

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Updated: Thursday, June 13, 2019
 
 

llround(3M)

Name

llround, llroundf, llroundl - round to nearest integer value

Synopsis

c99 [ flag... ] file... –lm [ library... ]
#include <math.h>

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

Description

These functions rounds their argument to the nearest integer value, rounding halfway cases away from 0 regardless of the current rounding direction.

Return Values

Upon successful completion, these functions return the rounded integer value.

If x is NaN, a domain error occurs and an unspecified value is returned.

If x is +Inf, a domain error occurs and an unspecified value is returned.

If x is -Inf, a domain error occurs and an unspecified value is returned.

If the correct value is positive and too large to represent as a long long, a domain error occurs and an unspecified value is returned.

If the correct value is negative and too large to represent as a long long, a domain error occurs and an unspecified value is returned.

Errors

These functions will fail if:

Domain Error

The x argument is NaN or ±Inf, or the correct value is not representable as an integer.

If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception will be raised.

Usage

An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions.

These functions differ from the llrint(3M) functions in that the default rounding direction for the llround() functions round halfway cases away from 0 and need not raise the inexact floating-point exception for non-integer arguments that round to within the range of the return type.

Attributes

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
Committed
Availability
system/library/math
MT-Level
MT-Safe
Standard

See Also

math.h(3HEAD), feclearexcept(3M), fetestexcept(3M), llrint(3M), lrint(3M), lround(3M), attributes(7), standards(7)