Namespaces
Variants
Views
Actions

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

From cppreference.com
< cpp‎ | algorithm
 
 
Algorithm library
Execution policies (C++17)
Non-modifying sequence operations
all_ofany_ofnone_of
(C++11)(C++11)(C++11)
(C++17)
Modifying sequence operations
Operations on uninitialized storage
Partitioning operations
Sorting operations
(C++11)
Binary search operations
Set operations (on sorted ranges)
Heap operations
(C++11)
Minimum/maximum operations
(C++11)
(C++17)
Permutations
Numeric operations
C library
 
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

Contents

[edit] Parameters

first, last - the range of elements to examine
policy - the execution policy to use. See execution policy for details.
p - unary predicate .

The signature of the predicate function should be equivalent to the following:

 bool pred(const Type &a);

While the signature does not need to have const &, the function must not modify the objects passed to it and must be able to accept all values of type (possibly const) Type regardless of value category (thus, Type & is not allowed, nor is Type unless for Type a move is equivalent to a copy (since C++11)).
The type Type must be such that an object of type InputIt can be dereferenced and then implicitly converted to Type. ​

Type requirements
-
InputIt must meet the requirements of InputIterator.
-
ForwardIt must meet the requirements of ForwardIterator.
-
UnaryPredicate must meet the requirements of Predicate.

[edit] 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.

[edit] Complexity

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

[edit] 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 three 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.

[edit] 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;
}

[edit] Example

#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

[edit] See also