W3cubDocs

/C++

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:

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.

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