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is_empty Class

Tests if type is an empty class.

template<class Ty>
    struct is_empty;

Ty

The type to query.

An instance of the type predicate holds true if the type Ty is an empty class, otherwise it holds false.

 

// std_tr1__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

Header: <type_traits>

Namespace: std

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