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

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:

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

#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

(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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