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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<> is a specialization of std::less with parameter and re- turn type deduced. Implementation-defined strict total order over pointers The function call operator yields the implementation-defined strict total order over pointers if the < operator between arguments invokes a built-in com- parison operator for a pointer, even if the built-in < operator does not. The implementation-defined strict total order is consistent with the partial order imposed by built-in comparison operators ( <=>, (since C++20)<, >, <=, and >=), and consistent among following stan- dard function objects: * std::less, std::greater, std::less_equal, and std::greater_equal, when the template argument is a pointer type or void * std::ranges::equal_to, std::ranges::not_equal_to, std::ranges::less, std::ranges::greater, std::ranges::less_equal, (since C++20) std::ranges::greater_equal, and std::compare_three_way Member types Member type Definition is_transparent /* unspecified */ Member functions operator() tests if the lhs compares less than rhs (public member function) std::less<>::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 The result of std::forward<T>(lhs) < std::forward<U>(rhs). If the comparison between both arguments resolves to a built-in com- parison operator for a pointer type, the implementation-defined strict total order is used for comparison after converting both arguments to pointers. Exceptions May throw implementation-defined exceptions. Notes The member type is_transparent indicates to the caller that this function object is a transparent function object: it accepts arguments of arbitrary types and uses perfect forwarding, which avoids unnecessary copying and conversion when the function object is used in heterogeneous context, or with rvalue ar- guments. In particular, template functions such as std::set::find and std::set::lower_bound make use of this member type on their Compare types. Example This section is incomplete Reason: no example http://cppreference.com 2022.07.31 std::less(3)
NAME | Synopsis | Member types | Member functions | Parameters | Return value | Exceptions | Notes | Example
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