NAME

std::isinf - std::isinf

Synopsis

Defined in header <cmath>
bool isinf( float arg ); (1) (since C++11)
(constexpr since C++23)
bool isinf( double arg ); (2) (since C++11)
(constexpr since C++23)
bool isinf( long double arg ); (3) (since C++11)
(constexpr since C++23)
bool isinf( IntegralType arg ); (4) (since C++11)
(constexpr since C++23)

1-3) Determines if the given floating-point number arg is a positive or negative
infinity.
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 is infinite, false otherwise

Example

// Run this code

#include <iostream>
#include <cmath>
#include <cfloat>

int main()
{
std::cout << std::boolalpha
<< "isinf(NaN) = " << std::isinf(NAN) << '\n'
<< "isinf(Inf) = " << std::isinf(INFINITY) << '\n'
<< "isinf(0.0) = " << std::isinf(0.0) << '\n'
<< "isinf(exp(800)) = " << std::isinf(std::exp(800)) << '\n'
<< "isinf(DBL_MIN/2.0) = " << std::isinf(DBL_MIN/2.0) << '\n';
}

Output:

isinf(NaN) = false
isinf(Inf) = true
isinf(0.0) = false
isinf(exp(800)) = true
isinf(DBL_MIN/2.0) = false

See also

fpclassify categorizes the given floating-point value
(C++11) (function)
isfinite checks if the given number has finite value
(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)