NAME

fpclassify, isfinite, isinf, isnan, isnormal, signbit, finite, finitef, isinff, isnanf — classify a floating-point number

SYNOPSIS

Math Library (libm, -lm)
#include <math.h>

int
fpclassify(real-floating x);

int
isfinite(real-floating x);

int
isinf(real-floating x);

int
isnan(real-floating x);

int
isnormal(real-floating x);

int
signbit(real-floating x);

DESCRIPTION

The fpclassify() macro takes an argument of x and returns one of the following manifest constants:

The isfinite() macro returns a non-zero value if and only if its argument has a finite (zero, subnormal, or normal) value.

The isinf(), isnan(), and isnormal() macros return non-zero if and only if x is an infinity, NaN, or a non-zero normalized number, respectively.

The signbit() macro takes an argument of x and returns non-zero if the value of its sign is negative, otherwise 0.

SEE ALSO

isgreater(3)

STANDARDS

The fpclassify(), isfinite(), isinf(), isnan(), isnormal(), and signbit() macros conform to ISO/IEC 9899:1999 (“ISO C99”).

The symbols isinff(), and isnanf() are provided as compatibility aliases to isinf(), and isnan(), respectively, and their uses are deprecated. Similarly, finite() and finitef() are deprecated versions of isfinite().

HISTORY

The fpclassify(), isfinite(), isinf(), isnan(), isnormal(), and signbit() macros were added in OpenBSD 4.4. 3BSD introduced isinf() and isnan() functions, which accepted double arguments; these have been superseded by the macros described above.