Linux manual pages Section 3  

Name

finite, finitef, finitel, isinf, isinff, isinfl, isnan, isnanf, isnanl — BSD floating-point classification functions

Synopsis

#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);
 
[Note] Note
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
finite(), finitef(), finitel():
_BSD_SOURCE || _SVID_SOURCE
isinf():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE;
or cc -std=c99
isinff(), isinfl():
_BSD_SOURCE || _SVID_SOURCE
isnan():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE || _ISOC99_SOURCE;
or cc -std=c99
isnanf(), isnanl():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600

DESCRIPTION

The finite() functions return a nonzero value if x is neither infinite nor a "not-a-number" (NaN) value, and 0 otherwise.

The isnan() functions return a nonzero value if x is a NaN value, and 0 otherwise.

The isinf() functions return 1 if x is positive infinity, −1 if x is negative infinity, and 0 otherwise.

NOTES

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).

SEE ALSO

fpclassify(3)

COLOPHON

This page is part of release 3.33 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://man7.org/linux/man-pages/.


  Copyright 2004 Andries Brouwer <aebcwi.nl>.

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