std::upper_bound

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C++
 
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功能
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all_of
any_of
none_of		（C++11）
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（C++11）
for_each
count
count_if
mismatch
equal
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Binary search operations (on sorted ranges)
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lower_bound
upper_bound
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Defined in header <algorithm>
template< class ForwardIt, class T >
ForwardIt upper_bound( ForwardIt first, ForwardIt last, const T& value );
 (1)
template< class ForwardIt, class T, class Compare >
ForwardIt upper_bound( ForwardIt first, ForwardIt last, const T& value, Compare comp );
 (2)
返回一个迭代器指向的第一个元素的范围内[first, last)是“更大的”比value。 operator<的第一个版本使用比较的元素，第二个版本使用给定的比较函数comp.
Original:
Returns an iterator pointing to the first element in the range [first, last) that is greater than value. The first version uses operator< to compare the elements, the second version uses the given comparison function comp.
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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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value -
值进行比较的元素
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value to compare the elements to
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comp - comparison function which returns ​true if the first argument is less than the second.

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

bool cmp(const Type1 &a, const Type2 &b);

The signature does not need to have const &, but the function must not modify the objects passed to it.
The type  Type1 must be such that an object of type T can be implicitly converted to  Type1. The type  Type2 must be such that an object of type ForwardIt can be dereferenced and then implicitly converted to  Type2. ​

Type requirements
-
ForwardIt must meet the requirements of ForwardIterator.

[编辑] 返回值

迭代器指向的第一个元素是“更大的”比value，或last如果没有找到这样的元素，.
Original:
iterator pointing to the first element that is greater than value, or last if no such element is found.
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[编辑] 可能的实现

First version 
template<class ForwardIt, class T>
ForwardIt upper_bound(ForwardIt first, ForwardIt last,
                            const T& value)
{
    ForwardIt it;
    std::iterator_traits<ForwardIt>::distance_type count, step;
    count = std::distance(first,last);
 
    while (count > 0) {
        it = first; 
        step = count / 2; 
        std::advance(it, step);
        if (!(value < *it)) {
            first = ++it;
            count -= step + 1;
        } else count = step;
    }
    return first;
}
Second version 
template<class ForwardIt, class T, class Compare>
ForwardIt upper_bound(ForwardIt first, ForwardIt last,
                            const T& value, Compare comp)
{
    ForwardIt it;
    std::iterator_traits<ForwardIt>::distance_type count, step;
    count = std::distance(first,last);
 
    while (count > 0) {
        it = first; 
        step = count / 2;
        std::advance(it, step);
        if (!comp(value, *it)),
            first = ++it;
            count -= step + 1
        } else count = step;
    }
    return first;
}

[编辑] 为例

#include <algorithm>
#include <iostream>
#include <iterator>
#include <vector>
 
int main()
{
    std::vector<int> data = { 1, 1, 2, 3, 3, 3, 3, 4, 4, 4, 5, 5, 6 };
 
    auto lower = std::lower_bound(data.begin(), data.end(), 4);
    auto upper = std::upper_bound(data.begin(), data.end(), 4);
 
    std::copy(lower, upper, std::ostream_iterator<int>(std::cout, " "));
}

Output: 

4 4 4

[编辑] 复杂性

的对数first和last之间的距离
Original:
logarithmic in the distance between first and last
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[编辑] 另请参阅
回报在一个特定的键匹配的元素
Original:
returns range of elements matching a specific key
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（函数模板） [edit]
返回一个迭代器的第一个元素“不低于”大于给定值
Original:
returns an iterator to the first element not less than the given value
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（函数模板） [edit]
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