on "cpp/language/operator comparison") (library support); adding three-way comparison to the library  |  201907L  |  [ ` <compare> ` ](/w/cpp/header/compare "cpp/header/compare") |  (C++20)  |  [ P0768R1 ](https://wg21.link/P0768R1)   
[ P1614R2 ](https://wg21.link/P1614R2)  
` __cpp_lib_to_address ` |  Utility to convert a pointer to a raw pointer (  std::to_address  )  |  201711L  |  [ ` <memory> ` ](/w/cpp/header/memory "cpp/header/memory") |  (C++20)  |  [ P0653R2 ](https://wg21.link/P0653R2)  
` __cpp_lib_to_array ` |  [ ` std::to_array ` ](/w/cpp/container/array/to_array "cpp/container/array/to array") |  201907L  |  [ ` <array> ` ](/w/cpp/header/array "cpp/header/array") |  (C++20)  |  [ P0325R4 ](https://wg21.link/P0325R4)  
` __cpp_lib_to_chars ` |  Elementary string conversions ( [ ` std::to_chars ` ](/w/cpp/utility/to_chars "cpp/utility/to chars") , [ ` std::from_chars ` ](/w/cpp/utility/from_chars "cpp/utility/from chars") )  |  201611L  |  [ ` <charconv> ` ](/w/cpp/header/charconv "cpp/header/charconv") |  (C++17)  |  [ P0067R5 ](https://wg21.link/P0067R5)   
[ P0682R1 ](https://wg21.link/P0682R1)  
[ LWG3137 ](https://wg21.link/LWG3137)  
Testing for success or failure of [ ` <charconv> ` ](/w/cpp/header/charconv "cpp/header/charconv") functions  |  202306L  |  [ ` <charconv> ` ](/w/cpp/header/charconv "cpp/header/charconv") |  (C++26)  |  [ P2497R0 ](https://wg21.link/P2497R0)  
` __cpp_lib_to_string ` |  Redefining  [ std::to_string ](/w/cpp/string/basic_string/to_string "cpp/string/basic string/to string") in terms of  [ std::format ](/w/cpp/utility/format/format "cpp/utility/format/format") |  202306L  |  [ ` <string> ` ](/w/cpp/header/string "cpp/header/string") |  (C++26)  |  [ P2587R3 ](https://wg21.link/P2587R3)  
` __cpp_lib_to_underlying ` |  [ ` std::to_underlying ` ](/w/cpp/utility/to_underlying "cpp/utility/to underlying") |  202102L  |  [ ` <utility> ` ](/w/cpp/header/utility "cpp/header/utility") |  (C++23)  |  [ P1682R2 ](https://wg21.link/P1682R2)  
` __cpp_lib_transformation_  trait_aliases ` |  Alias templates for TransformationTraits  |  201304L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++14)  |  [ N3655 ](https://wg21.link/N3655)  
` __cpp_lib_transparent_  operators ` |  Transparent operator functors (  std::less<> et al)  |  201210L  |  [ ` <functional> ` ](/w/cpp/header/functional "cpp/header/functional") |  (C++14)  |  [ N3421 ](https://wg21.link/N3421)  
Transparent  [ std::owner_less ](/w/cpp/memory/owner_less "cpp/memory/owner less") ( [ ` std::owner_less<void> ` ](/w/cpp/memory/owner_less_void "cpp/memory/owner less void") )  |  201510L  |  [ ` <memory> ` ](/w/cpp/header/memory "cpp/header/memory") [ ` <functional> ` ](/w/cpp/header/functional "cpp/header/functional") |  (C++17)  |  [ P0074R0 ](https://wg21.link/P0074R0)  
` __cpp_lib_tuple_element_t ` |  [ ` std::tuple_element_t ` ](/w/cpp/utility/tuple_element#Helper_types "cpp/utility/tuple element") |  201402L  |  [ ` <tuple> ` ](/w/cpp/header/tuple "cpp/header/tuple") |  (C++14)  |  [ N3887 ](https://wg21.link/N3887)  
` __cpp_lib_tuple_like ` |  Compatibility between  [ std::tuple ](/w/cpp/utility/tuple "cpp/utility/tuple") and tuple-like objects (  [ std::pair ](/w/cpp/utility/pair "cpp/utility/pair") ,  [ std::array ](/w/cpp/container/array "cpp/container/array") ,  std::subrange  )  |  202207L  |  [ ` <map> ` ](/w/cpp/header/map "cpp/header/map") [ ` <tuple> ` ](/w/cpp/header/tuple "cpp/header/tuple") [ ` <unordered_map> ` ](/w/cpp/header/unordered_map "cpp/header/unordered map") [ ` <utility> ` ](/w/cpp/header/utility "cpp/header/utility") |  (C++23)  |  [ P2165R4 ](https://wg21.link/P2165R4)  
Add tuple protocol to  [ std::complex ](/w/cpp/numeric/complex "cpp/numeric/complex") |  202311L  |  (C++26)  |  [ P2819R2 ](https://wg21.link/P2819R2)  
` __cpp_lib_tuples_by_type ` |  [ Addressing tuples by type ](/w/cpp/utility/tuple/get "cpp/utility/tuple/get") |  201304L  |  [ ` <tuple> `