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ranges_is_sorted.md

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is_sorted

  • algorithm[meta header]
  • std::ranges[meta namespace]
  • function template[meta id-type]
  • cpp20[meta cpp]
namespace std::ranges {
  template <forward_iterator I,
            sentinel_for<I> S,
            class Proj = identity,
            indirect_strict_weak_order<projected<I, Proj>> Comp = ranges::less>
  constexpr bool
    is_sorted(I first,
              S last,
              Comp comp = {},
              Proj proj = {}); // (1) C++20

  template <forward_range R,
            class Proj = identity,
            indirect_strict_weak_order<projected<iterator_t<R>, Proj>> Comp = ranges::less>
  constexpr bool
    is_sorted(R&& r,
              Comp comp = {},
              Proj proj = {}); // (2) C++20

  template <execution-policy Ep,
            random_access_iterator I,
            sized_sentinel_for<I> S,
            class Proj = identity,
            indirect_strict_weak_order<projected<I, Proj>> Comp = ranges::less>
  bool is_sorted(Ep&& exec,
                 I first,
                 S last,
                 Comp comp = {},
                 Proj proj = {}); // (3) C++26

  template <execution-policy Ep,
            sized-random-access-range R,
            class Proj = identity,
            indirect_strict_weak_order<projected<iterator_t<R>, Proj>> Comp = ranges::less>
  bool is_sorted(Ep&& exec,
                 R&& r,
                 Comp comp = {},
                 Proj proj = {}); // (4) C++26
}
  • ranges::less[link /reference/functional/ranges_less.md]
  • indirect_strict_weak_order[link /reference/iterator/indirect_strict_weak_order.md]
  • execution-policy[link /reference/execution/execution-policy.md]
  • random_access_iterator[link /reference/iterator/random_access_iterator.md]
  • sized_sentinel_for[link /reference/iterator/sized_sentinel_for.md]
  • sized-random-access-range[link /reference/ranges/sized-random-access-range.md]

概要

与えられた範囲がソート済みか判定する。

  • (1): イテレータ範囲を指定する
  • (2): Rangeを直接指定する
  • (3): (1)の並列アルゴリズム版。実行ポリシーを指定する
  • (4): (2)の並列アルゴリズム版。実行ポリシーを指定する

戻り値

例

基本的な使い方

#include <iostream>
#include <vector>
#include <algorithm>

int main()
{
  std::vector<int> v = {3, 1, 4, 2, 5};

  std::cout << std::boolalpha;
  std::cout << "before: is sorted? " << std::ranges::is_sorted(v) << std::endl;

  std::ranges::sort(v);

  std::cout << " after: is sorted? " << std::ranges::is_sorted(v) << std::endl;
}
  • std::ranges::sort[link ranges_sort.md]
  • std::ranges::is_sorted[color ff0000]

出力

before: is sorted? false
 after: is sorted? true

並列アルゴリズムの例 (C++26)

#include <iostream>
#include <vector>
#include <algorithm>
#include <execution>

int main()
{
  std::vector<int> v = {3, 1, 4, 1, 5, 9, 2, 6};

  std::cout << std::boolalpha;
  std::cout << "before: is sorted? "
            << std::ranges::is_sorted(std::execution::par, v) << std::endl;

  std::ranges::sort(v);

  std::cout << " after: is sorted? "
            << std::ranges::is_sorted(std::execution::par, v) << std::endl;
}
  • std::ranges::is_sorted[color ff0000]
  • std::ranges::sort[link ranges_sort.md]

出力

before: is sorted? false
 after: is sorted? true

バージョン

言語

  • C++20

処理系

参照