std::less(3) C++ Standard Libary std::less(3) NAME std::less - std::less Synopsis Defined in header <functional> template<> (since C++14) class less<void>; std::less<void> is a specialization of std::less with parameter and re- turn type deduced. Member functions operator() tests if lhs compares less than rhs (public member function) std::less<void>::operator() template< class T, class U > constexpr auto operator()( T&& lhs, U&& rhs ) const -> decltype(std::forward<T>(lhs) < std::forward<U>(rhs)); Returns the result of std::forward<T>(lhs) < std::forward<U>(rhs). Parameters lhs, rhs - values to compare Return value std::forward<T>(lhs) < std::forward<U>(rhs). If a built-in operator comparing pointers is called, the result is con- sistent with the implementation-defined strict total order over pointers. Exceptions May throw implementation-defined exceptions. Example // Run this code #include <algorithm> #include <functional> constexpr bool strictly_negative(int lhs) { return std::less<>()(lhs, 0); } int main() { constexpr signed low = 010; constexpr unsigned high = 10; std::less<> less{}; static_assert(less(low, high)); constexpr static auto arr = {0, -1, -2, -3, -4, -5}; static_assert(!std::all_of(arr.begin(), arr.end(), strictly_nega- tive)); static_assert(std::all_of(arr.begin() + 1, arr.end(), strictly_nega- tive)); } Defect reports The following behavior-changing defect reports were applied retroac- tively to previously published C++ standards. DR Applied to Behavior as published Correct behavior LWG 2562 C++98 the pointer total order might be guaranteed to be consistent inconsistent http://cppreference.com 2024.06.10 std::less(3)
NAME | Synopsis | Member functions | Parameters | Return value | Exceptions | Example
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