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

From cppreference.com
< cpp‎ | algorithm

Defined in header `<algorithm>` |  |
| (1) |
template< class InputIt, class UnaryPredicate > bool all_of( InputIt first, InputIt last, UnaryPredicate p ); |  | (since C++11) (until C++20)
template< class InputIt, class UnaryPredicate > constexpr bool all_of( InputIt first, InputIt last, UnaryPredicate p ); |  | (since C++20)
template< class ExecutionPolicy, class ForwardIt, class UnaryPredicate > bool all_of( ExecutionPolicy&& policy, ForwardIt first, ForwardIt last, UnaryPredicate p ); | (2) | (since C++17)
| (3) |
template< class InputIt, class UnaryPredicate > bool any_of( InputIt first, InputIt last, UnaryPredicate p ); |  | (since C++11) (until C++20)
template< class InputIt, class UnaryPredicate > constexpr bool any_of( InputIt first, InputIt last, UnaryPredicate p ); |  | (since C++20)
template< class ExecutionPolicy, class ForwardIt, class UnaryPredicate > bool any_of( ExecutionPolicy&& policy, ForwardIt first, ForwardIt last, UnaryPredicate p ); | (4) | (since C++17)
| (5) |
template< class InputIt, class UnaryPredicate > bool none_of( InputIt first, InputIt last, UnaryPredicate p ); |  | (since C++11) (until C++20)
template< class InputIt, class UnaryPredicate > constexpr bool none_of( InputIt first, InputIt last, UnaryPredicate p ); |  | (since C++20)
template< class ExecutionPolicy, class ForwardIt, class UnaryPredicate > bool none_of( ExecutionPolicy&& policy, ForwardIt first, ForwardIt last, UnaryPredicate p ); | (6) | (since C++17)

1) Checks if unary predicate `p` returns true for all elements in the range `[first, last)`.
3) Checks if unary predicate `p` returns true for at least one element in the range `[first, last)`.
5) Checks if unary predicate `p` returns true for no elements in the range `[first, last)`.
2,4,6) Same as (1,3,5), but executed according to `policy`. These overloads do not participate in overload resolution unless std::is_execution_policy_v < std::decay_t <ExecutionPolicy>> is true

### Parameters

first, last | - | the range of elements to examine
policy | - | the execution policy to use. See execution policy for details.
p | - | unary predicate . The expression p(v) must be convertible to bool for every argument `v` of type (possibly const) `VT`, where `VT` is the value type of `InputIt`, regardless of value category, and must not modify `v`. Thus, a parameter type of VT&is not allowed, nor is VT unless for `VT` a move is equivalent to a copy (since C++11). ​
Type requirements
- `InputIt` must meet the requirements of LegacyInputIterator.
- `ForwardIt` must meet the requirements of LegacyForwardIterator.
- `UnaryPredicate` must meet the requirements of Predicate.

### Return value

1-2) true if unary predicate returns true for all elements in the range, false otherwise. Returns true if the range is empty.
3-4) true if unary predicate returns true for at least one element in the range, false otherwise. Returns false if the range is empty.
5-6) true if unary predicate returns true for no elements in the range, false otherwise. Returns true if the range is empty.

### Complexity

1,3,5) At most `last` - `first` applications of the predicate
2,4,6) `O(last-first)` applications of the predicate

### Exceptions

The overloads with a template parameter named `ExecutionPolicy` report errors as follows:

- If execution of a function invoked as part of the algorithm throws an exception and `ExecutionPolicy` is one of the standard policies, std::terminate is called. For any other `ExecutionPolicy`, the behavior is implementation-defined.
- If the algorithm fails to allocate memory, std::bad_alloc is thrown.

### Possible implementation

First version

    template< class InputIt, class UnaryPredicate >
    constexpr bool all_of(InputIt first, InputIt last, UnaryPredicate p)
    {
        return std::find_if_not(first, last, p) == last;
    }

Second version

    template< class InputIt, class UnaryPredicate >
    constexpr bool any_of(InputIt first, InputIt last, UnaryPredicate p)
    {
        return std::find_if(first, last, p) != last;
    }

Third version

    template< class InputIt, class UnaryPredicate >
    constexpr bool none_of(InputIt first, InputIt last, UnaryPredicate p)
    {
        return std::find_if(first, last, p) == last;
    }

### Example

Run this code

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

    int main()
    {
        std::vector<int> v(10, 2);
        std::partial_sum(v.cbegin(), v.cend(), v.begin());
        std::cout << "Among the numbers: ";
        std::copy(v.cbegin(), v.cend(), std::ostream_iterator<int>(std::cout, " "));
        std::cout << '\n';

        if (std::all_of(v.cbegin(), v.cend(), [](int i){ return i % 2 == 0; })) {
            std::cout << "All numbers are even\n";
        }
        if (std::none_of(v.cbegin(), v.cend(), 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 (std::any_of(v.cbegin(), v.cend(), 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

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