finite, finitef, finitel, isinf, isinff, isinfl, isnan, isnanf, isnanl - BSD
floating-point classification functions
#include <math.h>
int finite(double x);
int finitef(float x);
int finitel(long double x);
int isinf(double x);
int isinff(float x);
int isinfl(long double x);
int isnan(double x);
int isnanf(float x);
int isnanl(long double x);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
finite(),
finitef(),
finitel():
/* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
isinf():
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
isinff(),
isinfl():
/* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
isnan():
_XOPEN_SOURCE || _ISOC99_SOURCE
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
isnanf(),
isnanl():
_XOPEN_SOURCE >= 600
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
The
finite(),
finitef(), and
finitel() functions return a
nonzero value if
x is neither infinite nor a "not-a-number"
(NaN) value, and 0 otherwise.
The
isnan(),
isnanf(), and
isnanl() functions return a
nonzero value if
x is a NaN value, and 0 otherwise.
The
isinf(),
isinff(), and
isinfl() functions return 1 if
x is positive infinity, -1 if
x is negative infinity, and 0
otherwise.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
finite (), finitef (), finitel (), isinf (), isinff (), isinfl (), isnan
(), isnanf (), isnanl () |
Thread safety |
MT-Safe |
Note that these functions are obsolete. C99 defines macros
isfinite(),
isinf(), and
isnan() (for all types) replacing them. Further
note that the C99
isinf() has weaker guarantees on the return value.
See
fpclassify(3).
fpclassify(3)