std::all_of, std::any_of, std::none_of
From cppreference.com
| Defined in header <algorithm>
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| template< class InputIt, class UnaryPredicate > bool all_of( InputIt first, InputIt last, UnaryPredicate p ); |
(1) | (since C++11) |
| template< class ExecutionPolicy, class InputIt, class UnaryPredicate > bool all_of( ExecutionPolicy&& policy, InputIt first, InputIt last, UnaryPredicate p ); |
(2) | (since C++17) |
| template< class InputIt, class UnaryPredicate > bool any_of( InputIt first, InputIt last, UnaryPredicate p ); |
(3) | (since C++11) |
| template< class ExecutionPolicy, class InputIt, class UnaryPredicate > bool any_of( ExecutionPolicy&& policy, InputIt first, InputIt last, UnaryPredicate p ); |
(4) | (since C++17) |
| template< class InputIt, class UnaryPredicate > bool none_of( InputIt first, InputIt last, UnaryPredicate p ); |
(5) | (since C++11) |
| template< class ExecutionPolicy, class InputIt, class UnaryPredicate > bool none_of( ExecutionPolicy&& policy, InputIt first, InputIt 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 trueContents |
[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); The signature does not need to have const &, but the function must not modify the objects passed to it. |
| Type requirements | ||
-InputIt must meet the requirements of InputIterator.
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-UnaryPredicate must meet the requirements of Predicate.
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[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
At most 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
ExecutionPolicyis one of the three standard policies, std::terminate is called. For any otherExecutionPolicy, the behavior is implementation-defined. - If the algorithm fails to allocate memory, std::bad_alloc is thrown.
[edit] Possible implementation
| First version |
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template< class InputIt, class UnaryPredicate > 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 > bool any_of(InputIt first, InputIt last, UnaryPredicate p) { return std::find_if(first, last, p) != last; } |
| Third version |
template< class InputIt, class UnaryPredicate > bool none_of(InputIt first, InputIt last, UnaryPredicate p) { return std::find_if(first, last, p) == last; } |
[edit] 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
[edit] See also
| (parallelism TS) |
parallelized version of std::all_of (function template) |
| (parallelism TS) |
parallelized version of std::any_of (function template) |
| (parallelism TS) |
parallelized version of std::none_of (function template) |