std::ranges::all_of,std::ranges::any_of,std::ranges::none_of (3) - Linux Man Pages

std::ranges::all_of,std::ranges::any_of,std::ranges::none_of: std::ranges::all_of,std::ranges::any_of,std::ranges::none_of

NAME

std::ranges::all_of,std::ranges::any_of,std::ranges::none_of - std::ranges::all_of,std::ranges::any_of,std::ranges::none_of

Synopsis


Defined in header <algorithm>
Call signature
template< InputIterator I, Sentinel<I> S, class Proj = std::identity,
IndirectUnaryPredicate<projected<I, Proj>> Pred > (1) (since C++20)
bool all_of( I first, S last, Pred pred, Proj proj = {} );
template< InputRange R, class Proj = std::identity,
IndirectUnaryPredicate<projected<ranges::iterator_t<R>, Proj>> Pred > (2) (since C++20)
bool all_of( R&& r, Pred pred, Proj proj = {} );
template< InputIterator I, Sentinel<I> S, class Proj = std::identity,
IndirectUnaryPredicate<projected<I, Proj>> Pred > (3) (since C++20)
bool any_of( I first, S last, Pred pred, Proj proj = {} );
template< InputRange R, class Proj = std::identity,
IndirectUnaryPredicate<projected<ranges::iterator_t<R>, Proj>> Pred > (4) (since C++20)
bool any_of( R&& r, Pred pred, Proj proj = {} );
template< InputIterator I, Sentinel<I> S, class Proj = std::identity,
IndirectUnaryPredicate<projected<I, Proj>> Pred > (5) (since C++20)
bool none_of( I first, S last, Pred pred, Proj proj = {} );
template< InputRange R, class Proj = std::identity,
IndirectUnaryPredicate<projected<ranges::iterator_t<R>, Proj>> Pred > (6) (since C++20)
bool none_of( R&& r, Pred pred, Proj proj = {} );


1) Checks if unary predicate pred returns true for all elements in the range [first, last) (after projecting with the projection proj).
3) Checks if unary predicate pred returns true for at least one element in the range [first, last) (after projecting with the projection proj).
5) Checks if unary predicate pred returns true for no elements in the range [first, last) (after projecting with the projection proj).
2,4,6) Same as (1,3,5), 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 may not be specified when calling any of them.
* None of them is visible to argument-dependent_lookup.
* When one of them is found by normal_unqualified_lookup for the name to the left of the function-call operator, it inhibits argument-dependent_lookup.


In practice, they may be implemented as function objects, or with special compiler extensions.

Parameters


first, last - the range of the elements to examine
r - the range of the elements to examine
pred - predicate to apply to the projected elements
proj - projection to apply to the elements

Return value


1-2) true if std::invoke(pred, std::invoke(proj, *i)) != false for every iterator i in the range, false otherwise. Returns true if the range is empty.
3-4) true if std::invoke(pred, std::invoke(proj, *i)) != false for at least one iterator i in the range, false otherwise. Returns false if the range is empty.
5-6) true if std::invoke(pred, std::invoke(proj, *i)) == false for every iterator i in the range, false otherwise. Returns true if the range is empty.

Complexity


At most last - first applications of the predicate and the projection.

Possible implementation

First version


  struct all_of_fn {
    template< InputIterator I, Sentinel<I> S, class Proj = std::identity,
              IndirectUnaryPredicate<projected<I, Proj>> Pred >
    bool operator()( I first, S last, Pred pred, Proj proj = {} ) const
    {
      return ranges::find_if_not(first, last, std::ref(pred), std::ref(proj)) == last;
    }


    template< InputRange R, class Proj = std::identity,
              IndirectUnaryPredicate<projected<ranges::iterator_t<R>, Proj>> Pred >
    bool operator()( R&& r, Pred pred, Proj proj = {} ) const
    {
      return operator()(ranges::begin(r), ranges::end(r), std::ref(pred), std::ref(proj));
    }
  };


  inline constexpr all_of_fn all_of;

Second version


  struct any_of_fn {
    template< InputIterator I, Sentinel<I> S, class Proj = std::identity,
              IndirectUnaryPredicate<projected<I, Proj>> Pred >
    bool operator()( I first, S last, Pred pred, Proj proj = {} ) const
    {
      return ranges::find_if(first, last, std::ref(pred), std::ref(proj)) != last;
    }


    template< InputRange R, class Proj = std::identity,
              IndirectUnaryPredicate<projected<ranges::iterator_t<R>, Proj>> Pred >
    bool operator()( R&& r, Pred pred, Proj proj = {} ) const
    {
      return operator()(ranges::begin(r), ranges::end(r), std::ref(pred), std::ref(proj));
    }
  };


  inline constexpr any_of_fn any_of;


Third version


  struct none_of_fn {
    template< InputIterator I, Sentinel<I> S, class Proj = std::identity,
              IndirectUnaryPredicate<projected<I, Proj>> Pred >
    bool operator()( I first, S last, Pred pred, Proj proj = {} ) const
    {
      return ranges::find_if(first, last, std::ref(pred), std::ref(proj)) == last;
    }


    template< InputRange R, class Proj = std::identity,
              IndirectUnaryPredicate<projected<ranges::iterator_t<R>, Proj>> Pred >
    bool operator()( R&& r, Pred pred, Proj proj = {} ) const
    {
      return operator()(ranges::begin(r), ranges::end(r), std::ref(pred), std::ref(proj));
    }
  };


  inline constexpr none_of_fn none_of;

Example


// Run this code


  #include <vector>
  #include <numeric>
  #include <algorithm>
  #include <iterator>
  #include <iterator>
  #include <iostream>
  #include <functional>


  namespace ranges = std::ranges;


  int main()
  {
      std::vector<int> v(10, 2);
      std::partial_sum(v.cbegin(), v.cend(), v.begin());
      std::cout << "Among the numbers: ";
      ranges::copy(v, std::ostream_iterator<int>(std::cout, " "));
      std::cout << '\n';


      if (ranges::all_of(v.cbegin(), v.cend(), [](int i){ return i % 2 == 0; })) {
          std::cout << "All numbers are even\n";
      }
      if (ranges::none_of(v, std::bind(std::modulus<int>(), std::placeholders::_1, 2))) {
          std::cout << "None of them are odd\n";
      }
      struct DivisibleBy
      {
          const int d;
          DivisibleBy(int n) : d(n) {}
          bool operator()(int n) const { return n % d == 0; }
      };


      if (ranges::any_of(v, DivisibleBy(7))) {
          std::cout << "At least one number is divisible by 7\n";
      }
  }

Output:


  Among the numbers: 2 4 6 8 10 12 14 16 18 20
  All numbers are even
  None of them are odd
  At least one number is divisible by 7

See also


all_of
any_of
none_of checks if a predicate is true for all, any or none of the elements in a range
        (function template)
(C++11)
(C++11)
(C++11)