Defined in header <cmath> | ||
|---|---|---|
| (1) | ||
int fpclassify( float num ); int fpclassify( double num ); int fpclassify( long double num ); | (since C++11) (until C++23) | |
constexpr int fpclassify( /* floating-point-type */ num ); | (since C++23) | |
| Additional overloads | ||
Defined in header <cmath> | ||
template< class Integer > int fpclassify( Integer num ); | (A) | (since C++11) (constexpr since C++23) |
num into the following categories: zero, subnormal, normal, infinite, NAN, or implementation-defined category. The library provides overloads of std::fpclassify for all cv-unqualified floating-point types as the type of the parameter num. (since C++23)
double
| num | - | floating-point or integer value |
one of FP_INFINITE, FP_NAN, FP_NORMAL, FP_SUBNORMAL, FP_ZERO or implementation-defined type, specifying the category of num.
The additional overloads are not required to be provided exactly as (A). They only need to be sufficient to ensure that for their argument num of integer type, std::fpclassify(num) has the same effect as std::fpclassify(static_cast<double>(num)).
#include <cfloat>
#include <cmath>
#include <iostream>
auto 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
|
(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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