floor(), floorf(), floorl()

Round down a value to the next integer

Synopsis:

#include <math.h>

double floor( double x );

float floorf( float x );

long double floorl(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 floor(), floorf(), and floorl() functions compute the largest integer less than or equal to x (rounding towards the “floor”).

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

Call feclearexcept(FE_ALL_EXCEPT) before calling floor(), floorf(), or floorl().
On return, if fetestexcept(FE_ALL_EXCEPT) is nonzero, then an error has occurred.

Returns:

The largest integer less than or equal to 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\n", floor( -3.14 ) );
    printf( "%f\n", floor( -3. ) );
    printf( "%f\n", floor( 0. ) );
    printf( "%f\n", floor( 3.14 ) );
    printf( "%f\n", floor( 3. ) );

    return EXIT_SUCCESS;
}

produces the output:

Classification:

ANSI, POSIX 1003.1

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