std::is_const

From Cppreference

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.

[edit] Equivalent definition

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 << boolalpha;
    std::cout << std::is_const<int>::value << '\n';
    std::cout << std::is_const<const int>::value  << '\n';
}

Output:

false
true

[edit] See also