Isinf
Defined in header <cmath>
.
Description
Determines if the given floating-point number num
is a positive or negative infinity.
The library provides overloads for all cv-unqualified floating-point types as the type of the parameter num
(od C++23).
Additional Overloads are provided for all integer types, which are treated as double.
Declarations
- C++23
- C++11
// 1)
constexpr bool isinf( /* floating-point-type */ num );
// 2)
template< class Integer >
constexpr bool isinf( Integer num );
// 1)
bool isinf( float num );
// 2)
bool isinf( double num );
// 3)
bool isinf( long double num );
// 4)
template< class Integer >
bool isinf( Integer num );
Parameters
num
- floating-point or integer value
Return value
true
if num
is infinite, false
otherwise.
Notes
The additional overloads are not required to be provided exactly as Additional Overloads.
They only need to be sufficient to ensure that for their argument num
of integer type,
std::isinf(num)
has the same effect as std::isinf(static_cast<double>(num))
.
Examples
#include <cfloat>
#include <cmath>
#include <iostream>
#include <limits>
int main()
{
const double max = std::numeric_limits<double>::max();
const double inf = std::numeric_limits<double>::infinity();
std::cout
<< std::boolalpha
<< "isinf(NaN) = "
<< std::isinf(NAN) << '\n'
<< "isinf(Inf) = "
<< std::isinf(INFINITY) << '\n'
<< "isinf(max) = "
<< std::isinf(max) << '\n'
<< "isinf(inf) = "
<< std::isinf(inf) << '\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';
}
isinf(NaN) = false
isinf(Inf) = true
isinf(max) = false
isinf(inf) = true
isinf(0.0) = false
isinf(exp(800)) = true
isinf(DBL_MIN/2.0) = false