floor, floorf, floorl

[アーティクル]
06/05/2017

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The latest version of this topic can be found at floor, floorf, floorl.

Calculates the floor of a value.

Syntax

double floor(  
   double x  
);  
float floor(  
   float x   
); // C++ only  
long double floor(  
   long double x  
); // C++ only  
float floorf(  
   float x  
);  
long double floorl(  
   long double x  
);

Parameters

x
Floating-point value.

Return Value

The floor functions return a floating-point value that represents the largest integer that is less than or equal to x. There is no error return.

Input	SEH Exception	Matherr Exception
± QNAN,IND	none	_DOMAIN

floor has an implementation that uses Streaming SIMD Extensions 2 (SSE2). For information and restrictions about using the SSE2 implementation, see _set_SSE2_enable.

Remarks

C++ allows overloading, so you can call overloads of floor that take and return float and long double values. In a C program, floor always takes and returns a double.

Requirements

Function	Required header
`floor`, `floorf`, `floorl`	<math.h>

For additional compatibility information, see Compatibility.

Example

// crt_floor.c  
// This example displays the largest integers  
// less than or equal to the floating-point values 2.8  
// and -2.8. It then shows the smallest integers greater  
// than or equal to 2.8 and -2.8.  
  
#include <math.h>  
#include <stdio.h>  
  
int main( void )  
{  
   double y;  
  
   y = floor( 2.8 );  
   printf( "The floor of 2.8 is %f\n", y );  
   y = floor( -2.8 );  
   printf( "The floor of -2.8 is %f\n", y );  
  
   y = ceil( 2.8 );  
   printf( "The ceil of 2.8 is %f\n", y );  
   y = ceil( -2.8 );  
   printf( "The ceil of -2.8 is %f\n", y );  
}

The floor of 2.8 is 2.000000  
The floor of -2.8 is -3.000000  
The ceil of 2.8 is 3.000000  
The ceil of -2.8 is -2.000000

.NET Framework Equivalent

System::Math::Floor

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