NAME

round, lround, llround — round to integral value, regardless of rounding direction

SYNOPSIS

#include <math.h>

double
round(double x);

long double
roundl(long double x);

float
roundf(float x);

long int
lround(double x);

long int
lroundl(long double x);

long int
lroundf(float x);

long long int
llround(double x);

long long int
llroundl(long double x);

long long int
llroundf(float x);

DESCRIPTION

The round() functions return the integral value nearest to x rounding half-way cases away from zero, regardless of the current rounding direction.

The lround() and llround() functions return the integral value nearest to x (rounding half-way cases away from zero, regardless of the current rounding direction) in the return formats specified. If the rounded value is outside the range of the return type, the numeric result is unspecified and the "invalid" floating-point exception is raised. A range error may occur if the magnitude of x is too large.

SPECIAL VALUES

round(±0) returns ±0.

round(±infinity) returns ±infinity.

The round() functions may, but are not required to, raise the "inexact" floating-point exception for non-integer numeric arguments.

The lround() and llround() functions need not raise the "inexact" floating-point exception for non-integer arguments that round to within the range of the return type.

NOTE

The roundtol() function is deprecated. Please use the C99 function lround() instead.

VECTOR OPERATIONS

If you need to apply the round() function to SIMD vectors or arrays, using the following functions provided by the Accelerate.framework may give significantly better performance:

#include <Accelerate/Accelerate.h>

vFloat vnintf(vFloat x);
void vvnintf(float *y, const float *x, const int *n);
void vvnint(double *y, const double *x, const int *n);

SEE ALSO

ceil(3), floor(3), trunc(3), math(3)

STANDARDS

The round() , lround() , and llround() functions conform to ISO/IEC 9899:2011.