is_empty Class
Tests if type is an empty class.
Syntax
template <class Ty>
struct is_empty;
Parameters
Ty
The type to query.
Remarks
An instance of the type predicate holds true if the type Ty is an empty class, otherwise it holds false.
Example
// std__type_traits__is_empty.cpp
// compile with: /EHsc
#include <type_traits>
#include <iostream>
struct empty
{
};
struct trivial
{
int val;
};
int main()
{
std::cout << "is_empty<trivial> == " << std::boolalpha
<< std::is_empty<trivial>::value << std::endl;
std::cout << "is_empty<empty> == " << std::boolalpha
<< std::is_empty<empty>::value << std::endl;
std::cout << "is_empty<int> == " << std::boolalpha
<< std::is_empty<int>::value << std::endl;
return (0);
}
is_empty<trivial> == false
is_empty<empty> == true
is_empty<int> == false
Requirements
Header: <type_traits>
Namespace: std