std:: isfinite

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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)
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

(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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