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std::ranges::max_element(3) C++ Standard Libary std::ranges::max_element(3) NAME std::ranges::max_element - std::ranges::max_element Synopsis Defined in header <algorithm> Call signature template< std::forward_iterator I, std::sentinel_for<I> S, class Proj = std::identity, std::indirect_strict_weak_order<std::projected<I, Proj>> Comp (1) (since = ranges::less > C++20) constexpr I max_element( I first, S last, Comp comp = {}, Proj proj = {} ); template< ranges::forward_range R, class Proj = std::identity, std::indirect_strict_weak_order< std::projected<ranges::iterator_t<R>, Proj>> Comp = (2) (since ranges::less > C++20) constexpr ranges::borrowed_iterator_t<R> max_element( R&& r, Comp comp = {}, Proj proj = {} ); 1) Finds the greatest element in the range [first, last). 2) Same as (1), but uses r as the source range, as if using ranges::begin(r) as first and ranges::end(r) as last. The function-like entities described on this page are niebloids, that is: * Explicit template argument lists cannot be specified when call- ing any of them. * None of them are visible to argument-dependent lookup. * When any of them are found by normal unqualified lookup as the name to the left of the function-call operator, argument-dependent lookup is in- hibited. In practice, they may be implemented as function objects, or with special compiler extensions. Parameters first, last - iterator-sentinel pair denoting the range to examine r - the range to examine comp - comparison to apply to the projected elements proj - projection to apply to the elements Return value Iterator to the greatest element in the range [first, last). If sev- eral elements in the range are equivalent to the greatest element, returns the itera- tor to the first such element. Returns last if the range is empty (i.e. if first == last). Complexity Exactly max(N - 1, 0) comparisons, where N = ranges::distance(first, last). Possible implementation struct max_element_fn { template<std::forward_iterator I, std::sentinel_for<I> S, class Proj = std::identity, std::indirect_strict_weak_order<std::projected<I, Proj>> Comp = ranges::less> constexpr I operator()(I first, S last, Comp comp = {}, Proj proj = {}) const { if (first == last) return last; auto largest = first; while (++first != last) if (std::invoke(comp, std::invoke(proj, *largest), std::in- voke(proj, *first))) largest = first; return largest; } template<ranges::forward_range R, class Proj = std::identity, std::indirect_strict_weak_order< std::projected<ranges::iterator_t<R>, Proj>> Comp = ranges::less> constexpr ranges::borrowed_iterator_t<R> operator()(R&& r, Comp comp = {}, Proj proj = {}) const { return (*this)(ranges::begin(r), ranges::end(r), std::ref(comp), std::ref(proj)); } }; inline constexpr max_element_fn max_element; Example // Run this code #include <algorithm> #include <cmath> #include <iostream> int main() { namespace ranges = std::ranges; const auto v = {3, 1, -14, 1, 5, 9, -14, 9}; auto result = ranges::max_element(v.begin(), v.end()); std::cout << "Max element at pos " << ranges::distance(v.begin(), result) << '\n'; auto abs_compare = [](int a, int b) { return std::abs(a) < std::abs(b); }; result = ranges::max_element(v, abs_compare); std::cout << "Absolute max element at pos " << ranges::distance(v.begin(), result) << '\n'; } Output: Max element at pos 5 Absolute max element at pos 2 See also ranges::min_element returns the smallest element in a range (C++20) (niebloid) ranges::minmax_element returns the smallest and the largest elements in a range (C++20) (niebloid) ranges::max returns the greater of the given values (C++20) (niebloid) max_element returns the largest element in a range (function template) http://cppreference.com 2024.06.10 std::ranges::max_element(3)
NAME | Synopsis | Parameters | Return value | Complexity | Possible implementation | Example | Output: | See also
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