is_union Class
The latest version of this topic can be found at is_union Class.
Tests if type is a union.
Syntax
template <class Ty>
struct is_union;
Parameters
Ty
The type to query.
Remarks
An instance of the type predicate holds true if the type Ty is a union type or a cv-qualified form of a union type, otherwise it holds false.
Example
// std_tr1__type_traits__is_union.cpp
// compile with: /EHsc
#include <type_traits>
#include <iostream>
struct trivial
{
int val;
};
union ints
{
int in;
long lo;
};
int main()
{
std::cout << "is_union<trivial> == " << std::boolalpha
<< std::is_union<trivial>::value << std::endl;
std::cout << "is_union<int> == " << std::boolalpha
<< std::is_union<int>::value << std::endl;
std::cout << "is_union<ints> == " << std::boolalpha
<< std::is_union<ints>::value << std::endl;
return (0);
}
is_union<trivial> == false
is_union<int> == false
is_union<ints> == true
Requirements
Header: <type_traits>
Namespace: std