round(), roundf(), roundl()

Round a number to the closest integer

Synopsis:

#include <math.h>

double round( double x );

float roundf( float x );

long double roundl( long double x );

Arguments:

x
The number you want to round.

Library:

libm

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

Description:

The round(), roundf(), and roundl() functions return x rounded to the nearest integer n, rounding halfway cases away from zero, regardless of the current rounding direction (i.e. returning the value with larger magnitude if |nx| == 1/2).

An application wishing to check for error situations should set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.

Returns:

The rounded value.

Examples:

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

int main (void)
{

  double num1, result1;

  for (num1 = 3.0; num1 <= 4.0; num1 += 0.1)
  {
    result1 = round (num1);
    printf ("Rounding %f gives %f\n", num1, result1);
  }

  return (EXIT_SUCCESS);
}

Classification:

ANSI, POSIX 1003.1

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

Last modified: 2013-12-23

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