std::isfinite

 

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)
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exp exp2 (C++11) expm1 (C++11)	log log10 log1p (C++11) log2 (C++11)
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sqrt cbrt (C++11)	hypot (C++11) pow
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sin cos tan asin acos atan atan2	sinh cosh tanh asinh (C++11) acosh (C++11) atanh (C++11)

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erf (C++11) erfc (C++11)	lgamma (C++11) tgamma (C++11)
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ceil floor roundlroundllround (C++11)(C++11)(C++11)	trunc (C++11) nearbyint (C++11) rintlrintllrint (C++11)(C++11)(C++11)
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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>
bool isfinite( float arg );	(1)	(since C++11) (constexpr since C++23)
bool isfinite( double arg );	(2)	(since C++11) (constexpr since C++23)
bool isfinite( long double arg );	(3)	(since C++11) (constexpr since C++23)
bool isfinite( IntegralType arg );	(4)	(since C++11) (constexpr since C++23)

1-3) Determines if the given floating point number arg has finite value i.e. it is normal, subnormal or zero, but not infinite or NaN.

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

true if arg has finite value, false otherwise

Examples

Run this code

#include <iostream>
#include <cmath>
#include <cfloat>
 
int main()
{
    std::cout << std::boolalpha
              << "isfinite(NaN) = " << std::isfinite(NAN) << '\n'
              << "isfinite(Inf) = " << std::isfinite(INFINITY) << '\n'
              << "isfinite(0.0) = " << std::isfinite(0.0) << '\n'
              << "isfinite(exp(800)) = " << std::isfinite(std::exp(800)) << '\n'
              << "isfinite(DBL_MIN/2.0) = " << std::isfinite(DBL_MIN/2.0) << '\n';
}

Output:

isfinite(NaN) = false
isfinite(Inf) = false
isfinite(0.0) = true
isfinite(exp(800)) = false
isfinite(DBL_MIN/2.0) = true

See also

fpclassify (C++11)	categorizes the given floating-point 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)