floor(), floorf(), floorl() — Round down to integral value

Standards

Standards / Extensions	C or C++	Dependencies
ISO C POSIX.1 XPG4 XPG4.2 ISO/ANSI C++ C99 Single UNIX Specification, Version 3 C++ TR1 C99	both

Format

#include <math.h>

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);

General description

Calculates the largest integer that is less than or equal to x.

Note: These functions work in both IEEE Binary Floating-Point and hexadecimal floating-point formats. See IEEE binary floating-point for more information about IEEE Binary Floating-Point.

Returned value

Returns the calculated integral value expressed as a double, float, or long double value. The result cannot have a range error.

Example

CELEBF24

/* CELEBF24                                      

   This example assigns y the value of the largest integer that is less         
   than or equal to 2.8, and it assigns z the value of the largest integer      
   that is less than or equal to -2.8.                                          

 */                                                                             
#include <math.h>                                                               
#include <stdio.h>                                                              
                                                                                
int main(void)                                                                  
{                                                                               
   double y, z;                                                                 
                                                                                
   y = floor(2.8);                                                              
   z = floor(-2.8);                                                             
                                                                                
   printf("floor(  2.8 ) = %f\n", y);                                           
   printf("floor( -2.8 ) = %f\n", z);                                           
}

Output

floor(  2.8 ) = 2.000000
floor( -2.8 ) = -3.000000