FP_NORMAL, FP_SUBNORMAL, FP_ZERO, FP_INFINITE, FP_NAN
From cppreference.com
| Defined in header <cmath>
|
||
#define FP_NORMAL /* implementation defined */ |
(since C++11) | |
#define FP_SUBNORMAL /* implementation defined */ |
(since C++11) | |
#define FP_ZERO /* implementation defined */ |
(since C++11) | |
#define FP_INFINITE /* implementation defined */ |
(since C++11) | |
#define FP_NAN /* implementation defined */ |
(since C++11) | |
The FP_NORMAL, FP_SUBNORMAL, FP_ZERO, FP_INFINITE, FP_NAN macros each represent a distinct category of floating-point numbers. They all expand to an integer constant expression.
| Constant | Explanation |
FP_NORMAL
|
indicates that the value is normal, i.e. not an infinity, subnormal, not-a-number or zero |
FP_SUBNORMAL
|
indicates that the value is subnormal |
FP_ZERO
|
indicates that the value is positive or negative zero |
FP_INFINITE
|
indicates that the value is not representable by the underlying type (positive or negative infinity) |
FP_NAN
|
indicates that the value is not-a-number (NaN) |
Example
Run this code
#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
See also
(C++11) |
categorizes the given floating-point value (function) |
C documentation for FP_categories
| |