std::all_of, std::any_of, std::none_of
Min standard notice:
Header: <algorithm>
- Checks if unary predicate p returns false for at least one element in the range [first,last).
# Declarations
template< class InputIt, class UnaryPred >
bool all_of( InputIt first, InputIt last, UnaryPred p );
(since C++11) (constexpr since C++20)
template< class ExecutionPolicy, class ForwardIt, class UnaryPred >
bool all_of( ExecutionPolicy&& policy,
ForwardIt first, ForwardIt last, UnaryPred p );
(since C++17)
template< class InputIt, class UnaryPred >
bool any_of( InputIt first, InputIt last, UnaryPred p );
(since C++11) (constexpr since C++20)
template< class ExecutionPolicy, class ForwardIt, class UnaryPred >
bool any_of( ExecutionPolicy&& policy,
ForwardIt first, ForwardIt last, UnaryPred p );
(since C++17)
template< class InputIt, class UnaryPred >
bool none_of( InputIt first, InputIt last, UnaryPred p );
(since C++11) (constexpr since C++20)
template< class ExecutionPolicy, class ForwardIt, class UnaryPred >
bool none_of( ExecutionPolicy&& policy,
ForwardIt first, ForwardIt last, UnaryPred p );
(since C++17)
# Parameters
first, last: the range of elements to examinepolicy: the execution policy to usep: 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).
# Example
#include <algorithm>
#include <functional>
#include <iostream>
#include <iterator>
#include <numeric>
#include <vector>
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<>(),
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";
}