std::isinf

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

#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

(C++11)
 categorizes the given floating point value
(function)
(C++11)
 checks if the given number has finite value
(function)
(C++11)
 checks if the given number is NaN
(function)
(C++11)
 checks if the given number is normal
(function)