<cmath> (math.h)

function
<cmath> <ctgmath>

rint

     double rint  (double x);
      float rintf (float x);
long double rintl (long double x);
     double rint (double x);
      float rint (float x);
long double rint (long double x);
     double rint (T x);           // additional overloads for integral types
Round to integral value
Rounds x to an integral value, using the rounding direction specified by fegetround.

This function may raise an FE_INEXACT exception if the value returned differs in value from x. See nearbyint for an equivalent function that cannot raise such exception.

Header <tgmath.h> provides a type-generic macro version of this function.
Additional overloads are provided in this header (<cmath>) for the integral types: These overloads effectively cast x to a double before calculations (defined for T being any integral type).

Parameters

x
Value to round.

Return Value

The value of x rounded to a nearby integral (as a floating-point value).
If this value differs from x, a FE_INEXACT exception may be raised (depending on the implementation).

Example

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/* rint example */
#include <stdio.h>      /* printf */
#include <fenv.h>       /* fegetround, FE_* */
#include <math.h>       /* rint */

int main ()
{
  printf ("rounding using ");
  switch (fegetround()) {
    case FE_DOWNWARD: printf ("downward"); break;
    case FE_TONEAREST: printf ("to-nearest"); break;
    case FE_TOWARDZERO: printf ("toward-zero"); break;
    case FE_UPWARD: printf ("upward"); break;
    default: printf ("unknown");
  }
  printf (" rounding:\n");

  printf ( "rint (2.3) = %.1f\n", rint(2.3) );
  printf ( "rint (3.8) = %.1f\n", rint(3.8) );
  printf ( "rint (-2.3) = %.1f\n", rint(-2.3) );
  printf ( "rint (-3.8) = %.1f\n", rint(-3.8) );
  return 0;
}


Possible output:

Rounding using to-nearest rounding:
rint (2.3) = 2.0
rint (3.8) = 4.0
rint (-2.3) = -2.0
rint (-3.8) = -4.0

See also