std::fpclassify
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 categories: zero, subnormal, normal, infinite, NAN, or implementation-defined category.
4) A set of overloads or a function template accepting the
arg
argument 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
#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
(C++11)
|
checks if the given number has finite value (function) |
(C++11)
|
checks if the given number is infinite (function) |
(C++11)
|
checks if the given number is NaN (function) |
(C++11)
|
checks if the given number is normal (function) |
provides an interface to query properties of all fundamental numeric types. (class template) |
|
C documentation for fpclassify |
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