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std::fpclassify(3) C++ Standard Libary std::fpclassify(3) NAME std::fpclassify - std::fpclassify Synopsis Defined in header <cmath> int fpclassify( float arg ); (1) (since C++11) (constexpr since C++23) int fpclassify( double arg ); (2) (since C++11) (constexpr since C++23) int fpclassify( long double arg ); (3) (since C++11) (constexpr since C++23) int fpclassify( IntegralType arg ); (4) (since C++11) (constexpr since C++23) 1-3) Categorizes floating point value arg into the following cate- gories: zero, subnormal, normal, infinite, NAN, or implementation-defined cate- gory. 4) A set of overloads or a function template accepting the arg argu- ment of any integral type. Equivalent to (2) (the argument is cast to double). Parameters arg - floating point value Return value one of FP_INFINITE, FP_NAN, FP_NORMAL, FP_SUBNORMAL, FP_ZERO or implementation-defined type, specifying the category of arg. Example // Run this code #include <iostream> #include <cmath> #include <cfloat> const char* show_classification(double x) { switch(std::fpclassify(x)) { case FP_INFINITE: return "Inf"; case FP_NAN: return "NaN"; case FP_NORMAL: return "normal"; case FP_SUBNORMAL: return "subnormal"; case FP_ZERO: return "zero"; default: return "unknown"; } } int main() { std::cout << "1.0/0.0 is " << show_classification(1/0.0) << '\n' << "0.0/0.0 is " << show_classification(0.0/0.0) << '\n' << "DBL_MIN/2 is " << show_classification(DBL_MIN/2) << '\n' << "-0.0 is " << show_classification(-0.0) << '\n' << "1.0 is " << show_classification(1.0) << '\n'; } Output: 1.0/0.0 is Inf 0.0/0.0 is NaN DBL_MIN/2 is subnormal -0.0 is zero 1.0 is normal See also isfinite checks if the given number has finite value (C++11) (function) isinf checks if the given number is infinite (C++11) (function) isnan checks if the given number is NaN (C++11) (function) isnormal checks if the given number is normal (C++11) (function) provides an interface to query properties of all fun- damental numeric numeric_limits types. (class template) http://cppreference.com 2022.07.31 std::fpclassify(3)
NAME | Synopsis | Parameters | Return value | Example | Output: | See also
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