std::fpclassify

From Cppreference

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Defined in header <cmath>
int fpclassify( float arg );		(since C++11)
int fpclassify( double arg );		(since C++11)
int fpclassify( long double arg );		(since C++11)

Categorizes floating point value arg into the following categories: zero, subnormal, normal, infinite, NAN, or implementation-defined category.

[edit] Parameters

arg

-

floating point value

[edit] Return value

one of FP_INFINITE, FP_NAN, FP_NORMAL, FP_SUBNORMAL, FP_ZERO or implementation-defined type, specifying the category of arg.

[edit] See also

isfinite (C++11)	checks if the given number has finite value (function)
isinf (C++11)	checks if the given number is infinite (function)
isnan (C++11)	checks if the given number is NaN (function)
isnormal (C++11)	checks if the given number is normal (function)
numeric_limits	provides an interface to query properties of all fundamental numeric types. (class template)