std::isfinite

 

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HUGE_VALFHUGE_VALHUGE_VALL (C++11)(C++11) math_errhandlingMATH_ERRNOMATH_ERREXCEPT (C++11)   INFINITY (C++11) NAN (C++11)	Classification FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C++11)(C++11)(C++11)(C++11)(C++11)

 

Defined in header <cmath>
	(1)
bool isfinite( float num ); bool isfinite( double num ); bool isfinite( long double num );			(since C++11) (until C++23)
constexpr bool isfinite( /*floating-point-type*/ num );			(since C++23)
SIMD overload (since C++26)
Defined in header <simd>
template< /*math-floating-point*/ V > constexpr typename /*deduced-simd-t*/<V>::mask_type   isfinite ( const V& v_num );		(S)	(since C++26)
Additional overloads
Defined in header <cmath>
template< class Integer > bool isfinite( Integer num );		(A)	(since C++11) (constexpr since C++23)

1) Determines if the given floating point number num has finite value i.e. it is normal, subnormal or zero, but not infinite or NaN. The library provides overloads for all cv-unqualified floating-point types as the type of the parameter num.(since C++23)

S) The SIMD overload performs an element-wise std::isfinite on v_num. (See math-floating-point and deduced-simd-t for their definitions.)

(since C++26)

A) Additional overloads are provided for all integer types, which are treated as double.

Parameters

num	-	floating-point or integer value
v_num	-	a data-parallel object of std::basic_simd specialization where its element type is a floating-point type

Return value

1) true if num has finite value, false otherwise.

S) A data-parallel mask object where the i^th element equals true if v_num[i] has finite value or false otherwise for all i in the range [​0​, v_num.size()).

Notes

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::isfinite(num) has the same effect as std::isfinite(static_cast<double>(num)).

Examples

Run this code

#include <cfloat>
#include <cmath>
#include <iostream>
 
int main()
{
    std::cout << std::boolalpha
              << "isfinite(NaN) = " << std::isfinite(NAN) << '\n'
              << "isfinite(Inf) = " << std::isfinite(INFINITY) << '\n'
              << "isfinite(-Inf) = " << std::isfinite(-INFINITY) << '\n'
              << "isfinite(HUGE_VAL) = " << std::isfinite(HUGE_VAL) << '\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(-Inf) = false
isfinite(HUGE_VAL) = 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)
C documentation for isfinite