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)
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)

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

Parameters

num

-

floating-point or integer value

Return value

true if num has finite value, false otherwise.

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