| Defined in header <cmath> | ||
|---|---|---|
int fpclassify( float arg ); | (1) | (since C++11) |
int fpclassify( double arg ); | (2) | (since C++11) |
int fpclassify( long double arg ); | (3) | (since C++11) |
int fpclassify( Integral arg ); | (4) | (since C++11) |
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
from 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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