rint(), rintf(), rintl()

Round to the nearest integral value

Synopsis:

#include <math.h>

double rint ( double x );

float rintf ( float x );

long double rintl( long double x );

Arguments:

x
The number that you want to round.

Library:

libm

Use the -l m option to qcc to link against this library.

Description:

The rint(), rintf(), and rintl() functions return the integral value nearest x in the direction of the current rounding mode (see fesetround()).

If the current rounding mode rounds toward negative infinity, then rint() is identical to floor(). If the current rounding mode rounds toward positive infinity, then rint() is identical to ceil().

To check for error situations, use feclearexcept() and fetestexcept():

Returns:

An integer (represented as a double precision number) nearest x in the direction of the current rounding mode. The result has the same sign as x.

If x is: rint() returns:
±Inf x
NaN NaN

Examples:

#include <stdio.h>
#include <math.h>
#include <fenv.h>
#include <stdlib.h>

int main( void )
{
    int except_flags;
    double a, b;

    feclearexcept(FE_ALL_EXCEPT);
    a = 0.7 ;
    b = rint(a);

    except_flags = fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW);
    if(except_flags) {
        /* An error occurred; handle it appropriately. */
    }

    printf("Round Native mode %f -> %f \n", a, b);

    return EXIT_SUCCESS;
}

Classification:

ANSI, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler No
Signal handler No
Thread Yes