lround

, lroundf

, lroundl

- round to nearest integer value

Synopsis

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

long lround(double x);

long lroundf(float x);

long lroundl(long double x);

Description

These functions round their argument to the nearest integer value, rounding halfway cases away from zero, 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, a domain error occurs and an unspecified value is returned.

If the correct value is negative and too large to represent as a 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 is 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.

Attributes

See attributes(5) for descriptions of the following attributes:

See Also

feclearexcept(3M), fetestexcept(3M), llround(3M), math.h(3HEAD), attributes(5), standards(5)