std::all_of, std::any_of, std::none_of
cppreference.com
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| <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 InputIt, class UnaryPredicate > bool any_of( InputIt first, InputIt last, UnaryPredicate p ); |
(2) | (since C++11) |
template< class InputIt, class UnaryPredicate > bool none_of( InputIt first, InputIt last, UnaryPredicate p ); |
(3) | (since C++11) |
1)
p [first, last) true .2)
p [first, last) true .3)
p [first, last) true .| first, last | - | . |
| p | - | . (signature) :
(signature) |
-InputIt : InputIterator.
| ||
-UnaryPredicate : Predicate.
| ||
1)
true true, false. true .2)
true true, false. false .3)
true true, false. true . last - first .
| First version |
|---|
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;
}
|
#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