std::isfinite

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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)
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
(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
S) A data-parallel mask object where the ith 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

(C++11)
 categorizes the given floating-point 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)
C documentation for isfinite
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