C++ version of isnormal()

Question

Is there a C++ version of the isnormal, isnan and so C functions? I know I can use the C functions from C++, but I'm always interested to know if there are some C++-only alternatives.

Answer 1

There is no such a functionality in stl. You could check that in reference: cppreference

C functionalities was placed in C++ and APIs are available through headers without postfix "*.h" and with prefix "c" example

<cstdlib>

But I'm certain You know about it.

If You're looking for something simmilar you probably would find many C like functions in amazing boost library. Most of classes would be introduced to new C++ standard so its worth to learn.

boost

Answer 2

Exact duplicate question

Note: isnan, isnormal and similars are quite easy to redefine as due to IEEE standards there are simple rules (respected in float/double C++ implementation) to check whether a number is "finite" or not. I.E. if "a is nan" then "a is != a".

Answer 3

Boost has some versions of the same.

Answer 4

Not as far as I know. Doesn't look like there's one in the STL. Since that's such a simple function I would guess they didn't want to take the time to replace it. The old C version works fine. I would say just continue to use the C isnormal().

Answer 5

They're included in <cmath> in the C++0x draft:

template <class T> int fpclassify(T x);
template <class T> bool isfinite(T x);
template <class T> bool isinf(T x);
template <class T> bool isnan(T x);
template <class T> bool isnormal(T x);