ceil(), ceilf(), ceill()

Round up a value to the next integer

Synopsis:

#include <math.h>

double ceil( double x );

float ceilf( float x );

long double ceill( long double x );

Arguments:

x: The value you want to round.

Library:

libm

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

Description:

The ceil(), ceilf(), and ceill() functions round the value of x up to the next integer (rounding towards the “ceiling”).

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

Call feclearexcept(FE_ALL_EXCEPT) before calling ceil(), ceilf(), or ceill().
On return, if fetestexcept(FE_ALL_EXCEPT) is nonzero, then an error has occurred.

Returns:

The smallest integer ≥ x with the same sign as x.

If `x` is:	These functions return:	Errors:
±0.0	`x`	—
±Inf	`x`	—
NaN	NaN	—

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.

Examples:

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

int main( void )
{
    printf( "%f %f %f %f %f\n", ceil( -2.1 ), 
      ceil( -2. ), ceil( 0.0 ), ceil( 2. ), 
      ceil( 2.1 ) );

    return EXIT_SUCCESS;
}

produces the output:

-2.000000 -2.000000 0.000000 2.000000 3.000000

Classification:

ANSI, POSIX 1003.1

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