# floorf (3)

# NAME

floor, floorf, floorl - largest integral value not greater than argument# SYNOPSIS

#include <math.h>

Link withdouble floor(doublex);float floorf(floatx);long double floorl(long doublex);

*-lm*.

Feature Test Macro Requirements for glibc (see

**feature_test_macros**(7)):

**floorf**(),

**floorl**():

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

|| /* Since glibc 2.19: */ _DEFAULT_SOURCE

|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

|| /* Since glibc 2.19: */ _DEFAULT_SOURCE

|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

# DESCRIPTION

These functions return the largest integral value that is not greater than*x*. For example,

*floor(0.5)*is 0.0, and

*floor(-0.5)*is -1.0.

# RETURN VALUE

These functions return the floor of*x*. If

*x*is integral, +0, -0, NaN, or an infinity,

*x*itself is returned.

# ERRORS

No errors occur. POSIX.1-2001 documents a range error for overflows, but see NOTES.# ATTRIBUTES

For an explanation of the terms used in this section, see**attributes**(7).

Interface | Attribute | Value |

floor (), floorf (), floorl () | Thread safety | MT-Safe |

# CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008. The variant returning*double*also conforms to SVr4, 4.3BSD, C89.

# NOTES

SUSv2 and POSIX.1-2001 contain text about overflow (which might set*errno*to

**ERANGE**, or raise an

**FE_OVERFLOW**exception). In practice, the result cannot overflow on any current machine, so this error-handling stuff is just nonsense. (More precisely, overflow can happen only when the maximum value of the exponent is smaller than the number of mantissa bits. For the IEEE-754 standard 32-bit and 64-bit floating-point numbers the maximum value of the exponent is 128 (respectively, 1024), and the number of mantissa bits is 24 (respectively, 53).)

# SEE ALSO

**ceil**(3),

**lrint**(3),

**nearbyint**(3),

**rint**(3),

**round**(3),

**trunc**(3)