Manpages - finite.3

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 <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

  isinf():
      _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE
          || /* Glibc since 2.19: */ _DEFAULT_SOURCE
          || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

*isinff*(), *isinfl*():

      /* Glibc since 2.19: */ _DEFAULT_SOURCE
          || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

*isnan*():

      _XOPEN_SOURCE || _ISOC99_SOURCE
          || /* Glibc since 2.19: */ _DEFAULT_SOURCE
          || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

*isnanf*(), *isnanl*():

      _XOPEN_SOURCE >= 600
          || /* Glibc since 2.19: */ _DEFAULT_SOURCE
          || /* Glibc <= 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).

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)

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