std::ranges::all_of, std::ranges::any_of, std::ranges::none_of - cppreference.com (original) (raw)

1. Checks if unary predicate pred returns false for at least one element in the range [first, last) (after projecting with the projection proj).

2. Checks if unary predicate pred returns true for at least one element in the range [first, last) (after projecting with the projection proj).

3. Checks if unary predicate pred returns true for none of the 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 algorithm function objects (informally known as 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.

Contents

• 1 Parameters
• 2 Return value
• 3 Complexity
• 4 Possible implementation
• 5 Example
• 6 See also

[edit] Parameters

[edit] 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.

1. ↑ The range is empty in this case.

[edit] Complexity

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

[edit] Possible implementation

[edit] Example

#include #include #include #include #include #include   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 v(10, 2); std::partial_sum(v.cbegin(), v.cend(), v.begin()); std::cout << "Among the numbers: "; ranges::copy(v, std::ostream_iterator(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(), 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

[edit] See also

| | checks if a predicate is true for all, any or none of the elements in a range (function template) [edit] | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |