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

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< cpp‎ | algorithm‎ | ranges

Defined in header `<algorithm>` |  |
Call signature |  |
template< std::input_iterator I, std::sentinel_for<I> S, class Proj = std::identity, std::indirect_unary_predicate<std::projected<I, Proj>> Pred > constexpr bool all_of( I first, S last, Pred pred, Proj proj = {} ); | (1) | (since C++20)
template< ranges::input_range R, class Proj = std::identity, std::indirect_unary_predicate< std::projected<ranges::iterator_t<R>,Proj>> Pred > constexpr bool all_of( R&& r, Pred pred, Proj proj = {} ); | (2) | (since C++20)
template< std::input_iterator I, std::sentinel_for<I> S, class Proj = std::identity, std::indirect_unary_predicate<std::projected<I, Proj>> Pred > constexpr bool any_of( I first, S last, Pred pred, Proj proj = {} ); | (3) | (since C++20)
template< ranges::input_range R, class Proj = std::identity, std::indirect_unary_predicate< std::projected<ranges::iterator_t<R>,Proj>> Pred > constexpr bool any_of( R&& r, Pred pred, Proj proj = {} ); | (4) | (since C++20)
template< std::input_iterator I, std::sentinel_for<I> S, class Proj = std::identity, std::indirect_unary_predicate<std::projected<I, Proj>> Pred > constexpr bool none_of( I first, S last, Pred pred, Proj proj = {} ); | (5) | (since C++20)
template< ranges::input_range R, class Proj = std::identity, std::indirect_unary_predicate< std::projected<ranges::iterator_t<R>,Proj>> Pred > constexpr 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 cannot be specified when calling 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 inhibited.

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.

See also Notes below.

### Complexity

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

### Possible implementation

all_of (1-2)
    struct all_of_fn
    {
        template<std::input_iterator I, std::sentinel_for<I> S, class Proj = std::identity,
                 std::indirect_unary_predicate<std::projected<I, Proj>> Pred>
        constexpr 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<ranges::input_range R, class Proj = std::identity,
                 std::indirect_unary_predicate<
                     std::projected<ranges::iterator_t<R>,Proj>> Pred>
        constexpr 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;
any_of (3-4)
    struct any_of_fn
    {
        template<std::input_iterator I, std::sentinel_for<I> S, class Proj = std::identity,
                 std::indirect_unary_predicate<std::projected<I, Proj>> Pred>
        constexpr 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<ranges::input_range R, class Proj = std::identity,
                 std::indirect_unary_predicate<
                     std::projected<ranges::iterator_t<R>,Proj>> Pred>
        constexpr 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;
none_of (5-6)
    struct none_of_fn
    {
        template<std::input_iterator I, std::sentinel_for<I> S, class Proj = std::identity,
                 std::indirect_unary_predicate<std::projected<I, Proj>> Pred>
        constexpr 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<ranges::input_range R, class Proj = std::identity,
                 std::indirect_unary_predicate<
                     std::projected<ranges::iterator_t<R>,Proj>> Pred>
        constexpr 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;

### Notes

The return value represented in the form of the Truth table is:

| input range contains
| all true, none false | some true, some false | none true, all false | none true, none false (empty range)
1–2) all_of | true | false | false | true
3–4) any_of | true | true | false | false
5–6) none_of | false | false | true | true

### Example

Run this code

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

    namespace ranges = std::ranges;

    constexpr bool some_of(auto&& r, auto&& pred) // some but not all
    {
        return not (ranges::all_of(r, pred) or ranges::none_of(r, pred));
    }

    constexpr auto w = { 1, 2, 3 };
    static_assert(!some_of(w, [](int x) { return x < 1; }));
    static_assert( some_of(w, [](int x) { return x < 2; }));
    static_assert(!some_of(w, [](int x) { return x < 4; }));

    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";

        auto DivisibleBy = [](int d)
        {
            return [d](int m) { return m % 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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