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std::is_const

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Defined in header <type_traits>
template< class T >
struct is_const;
(since C++11)

If T is a const-qualified type (that is, const, or const volatile), provides the member constant value equal true. For any other type, value is false.

Contents

Inherited from std::integral_constant

Member constants

value
[static]
true if T is a const-qualified type , false otherwise
(public static member constant)

Member functions

operator bool
converts the object to bool, returns value
(public member function)

Member types

Type Definition
value_type bool
type std::integral_constant<bool, value>

[edit] Possible implementation

template<class T> struct is_const          : std::false_type {};
template<class T> struct is_const<const T> : std::true_type {};

[edit] Example

#include <iostream>
#include <type_traits>
 
int main() 
{
    std::cout << std::boolalpha;
    std::cout << std::is_const<int>::value << '\n';
    std::cout << std::is_const<const int>::value  << '\n';
}

Output:

false
true

[edit] See also

checks if a type is volatile-qualified
(class template) [edit]