std::same_as - cppreference.com (original) (raw)

| | | | | ------------------------------------------------------------------- | | ------------- | | template< class T, class U >concept same_as = /* see below */; | | (since C++20) |

The concept same_as<T, U> is satisfied if and only if T and U denote the same type.

std::same_as<T, U> subsumes std::same_as<U, T> and vice versa.

[edit] Possible implementation

namespace detail { template< class T, class U > concept SameHelper = std::is_same_v<T, U>; }   template< class T, class U > concept same_as = detail::SameHelper<T, U> && detail::SameHelper<U, T>;

[edit] Example

#include #include   template<typename T, typename ... U> concept either = (std::same_as<T, U> || ...);   template concept is_printable = std::integral || std::floating_point || either<std::remove_cvref_t<std::remove_pointer_t<std::decay_t>>, char, wchar_t>;   void println(is_printable auto const ... arguments) { (std::wcout << ... << arguments) << '\n'; }   int main() { println("Example: ", 3.14, " : ", 42, " : [", 'a', L'-', L"Z]"); }

Output:

Example: 3.14 : 42 : [a-Z]

[edit] References

[edit] See also

| | checks if two types are the same (class template) [edit] | | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |