std::fpclassify

 

C++

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Common mathematical functions

Functions
Basic operations
abs(int)labsllabsimaxabs (C++11) abs(float)fabs divldivlldivimaxdiv (C++11) fmod	remainder (C++11) remquo (C++11) fma (C++11) fmax (C++11) fmin (C++11) fdim (C++11) nannanfnanl (C++11)(C++11)(C++11)
Exponential functions
exp exp2 (C++11) expm1 (C++11)	log log10 log1p (C++11) log2 (C++11)
Power functions
sqrt cbrt (C++11)	hypot (C++11) pow
Trigonometric and hyperbolic functions
sin cos tan asin acos atan atan2	sinh cosh tanh asinh (C++11) acosh (C++11) atanh (C++11)

Error and gamma functions
erf (C++11) erfc (C++11)	lgamma (C++11) tgamma (C++11)
Nearest integer floating point operations
ceil floor roundlroundllround (C++11)(C++11)(C++11)	trunc (C++11) nearbyint (C++11) rintlrintllrint (C++11)(C++11)(C++11)
Floating point manipulation functions
ldexp scalbnscalbln (C++11)(C++11) ilogb (C++11) logb (C++11)	frexp modf nextafternexttoward (C++11)(C++11) copysign (C++11)
Classification/Comparison
fpclassify (C++11) isfinite (C++11) isinf (C++11) isnan (C++11) isnormal (C++11) signbit (C++11)	isgreater (C++11) isgreaterequal (C++11) isless (C++11) islessequal (C++11) islessgreater (C++11) isunordered (C++11)
Macro constants
HUGE_VALFHUGE_VALHUGE_VALL (C++11)(C++11) INFINITY (C++11) NAN (C++11) math_errhandlingMATH_ERRNOMATH_ERREXCEPT (C++11)	FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C++11)(C++11)(C++11)(C++11)(C++11)

 

Defined in header <cmath>
int fpclassify( float arg );		(since C++11)
int fpclassify( double arg );		(since C++11)
int fpclassify( long double arg );		(since C++11)

Categorizes floating point value arg into the following categories: zero, subnormal, normal, infinite, NAN, or implementation-defined category.

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>
 
int main() {
    std::cout<<"FP_NAN       = "<<FP_NAN      <<'\n';// 0
    std::cout<<"FP_INFINITE  = "<<FP_INFINITE <<'\n';// 1
    std::cout<<"FP_ZERO      = "<<FP_ZERO     <<'\n';// 2
    std::cout<<"FP_SUBNORMAL = "<<FP_SUBNORMAL<<'\n';// 3
    std::cout<<"FP_NORMAL    = "<<FP_NORMAL   <<'\n';// 4
    std::cout<<'\n';
    std::cout<<"std::fpclassify(NAN)         = "<<std::fpclassify(NAN)        <<'\n';
    std::cout<<"std::fpclassify(INFINITY)    = "<<std::fpclassify(INFINITY)   <<'\n';
    std::cout<<"std::fpclassify(0.f)         = "<<std::fpclassify(0.f)        <<'\n';
    std::cout<<"std::fpclassify(FLT_MIN/2.f) = "<<std::fpclassify(FLT_MIN/2.f)<<'\n';
    std::cout<<"std::fpclassify(1.f)         = "<<std::fpclassify(1.f)        <<'\n';
 
    return 0;
}

Possible output:

FP_NAN       = 0
FP_INFINITE  = 1
FP_ZERO      = 2
FP_SUBNORMAL = 3
FP_NORMAL    = 4
 
fpclassify(NAN)         = 0
fpclassify(INFINITY)    = 1
fpclassify(0.f)         = 2
fpclassify(FLT_MIN/2.f) = 3
fpclassify(1.f)         = 4

See also

isfinite (C++11)	checks if the given number has finite value (function)
isinf (C++11)	checks if the given number is infinite (function)
isnan (C++11)	checks if the given number is NaN (function)
isnormal (C++11)	checks if the given number is normal (function)
numeric_limits	provides an interface to query properties of all fundamental numeric types. (class template)
C documentation for fpclassify