NAME

std::isfinite - std::isfinite

Synopsis

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 categorizes the given floating-point value
(C++11) (function)
isinf checks if the given number is infinite
(C++11) (function)
isnan checks if the given number is NaN
(C++11) (function)
isnormal checks if the given number is normal
(C++11) (function)