floor, floorf, floorl - largest integral value not greater than argument
Math library (
libm,
-lm)
#include <math.h>
double floor(double x);
float floorf(float x);
long double floorl(long double x);
floorf(),
floorl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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.
These functions return the floor of
x.
If
x is integral, +0, -0, NaN, or an infinity,
x itself is
returned.
No errors occur. POSIX.1-2001 documents a range error for overflows, but see
NOTES.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
floor (), floorf (), floorl () |
Thread safety |
MT-Safe |
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning
double also conforms to SVr4, 4.3BSD.
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 127 (respectively, 1023), and the number of mantissa bits
including the implicit bit is 24 (respectively, 53).)
ceil(3),
lrint(3),
nearbyint(3),
rint(3),
round(3),
trunc(3)