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

From cppreference.com
< cpp‎ | algorithm‎ | ranges

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

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

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