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

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算法库
功能
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Functions
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修改序列操作
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Non-modifying sequence operations
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all_of
any_of
none_of
(C++11)
(C++11)
(C++11)
for_each
count
count_if
mismatch
equal
修改序列操作
Original:
Modifying sequence operations
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分区操作
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Partitioning operations
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is_partitioned(C++11)
partition
partition_copy(C++11)
排序操作(排序的区间)
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Sorting operations (on sorted ranges)
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is_sorted(C++11)
is_sorted_until(C++11)
sort
二进制搜索操作(排序的区间)
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Binary search operations (on sorted ranges)
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设置操作(排序的区间)
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Set operations (on sorted ranges)
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堆的操作
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Heap operations
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最小/最大操作
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Minimum/maximum operations
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数字操作
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Numeric operations
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C库
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C library
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Defined in header <algorithm>
template< class InputIt, class UnaryPredicate >
bool all_of( InputIt first, InputIt last, UnaryPredicate p );
(1) (C++11 起)
template< class InputIt, class UnaryPredicate >
bool any_of( InputIt first, InputIt last, UnaryPredicate p );
(2) (C++11 起)
template< class InputIt, class UnaryPredicate >
bool none_of( InputIt first, InputIt last, UnaryPredicate p );
(3) (C++11 起)
1)
一元谓词检查是否p回报true范围内的所有元素[first, last).
Original:
Checks if unary predicate p returns true for all elements in the range [first, last).
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2)
一元谓词检查是否p回报true的范围内至少有一个元素[first, last).
Original:
Checks if unary predicate p returns true for at least one element in the range [first, last).
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3)
一元谓词检查是否p回报true的范围内没有任何元素[first, last).
Original:
Checks if unary predicate p returns true for no elements in the range [first, last).
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目录

[编辑] 参数

first, last -
检查的元素
Original:
the range of elements to examine
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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.
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.

[编辑] 返回值

1)
true如果一元谓词返回true范围内的所有元素,false不然。返回true的范围内是空
Original:
true if unary predicate returns true for all elements in the range, false otherwise. Returns true if the range is empty.
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2)
true如果一元谓词返回true的范围内至少有一个元素,false不然。返回false的范围内是空
Original:
true if unary predicate returns true for at least one element in the range, false otherwise. Returns false if the range is empty.
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3)
true如果一元谓词返回true的范围内没有任何元素,false不然。返回true的范围内是空
Original:
true if unary predicate returns true for no elements in the range, false otherwise. Returns true if the range is empty.
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[编辑] 复杂性

在最last - first谓词的应用
Original:
At most last - first applications of the predicate
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[编辑] 可能的实现

First version
template< class InputIt, class UnaryPredicate >
bool all_of(InputIt first, InputIt last, UnaryPredicate p)
{
    for (; first != last; ++first) {
        if (!p(*first)) return false;
    }
    return true;
}
Second version
template< class InputIt, class UnaryPredicate >
bool any_of(InputIt first, InputIt last, UnaryPredicate p)
{
    for (; first != last; ++first) {
        if (p(*first)) return true;
    }
    return false;
}
Third version
template< class InputIt, class UnaryPredicate >
bool none_of(InputIt first, InputIt last, UnaryPredicate p)
{
    for (; first != last; ++first) {
        if (p(*first)) return false;
    }
    return true;
}

[编辑] 为例

#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