我需要一个二进制搜索算法，它与C ++标准的容器，像兼容的的std :: binary_search的在标准库中的 ＆LT;算法＆GT; 头，但不同的std :: binary_search的，我需要它返回一个指向在结果迭代器，而不是一个简单的布尔如果该元素存在，告诉我

I need a binary search algorithm that is compatible with the C++ standard containers, something like std::binary_search in the standard library's <algorithm> header, but unlike std::binary_search, I need it to return the iterator that points at the result, not a simple boolean telling me if the element exists

（在一个侧面说明，什么是地狱是当他们定义的binary_search的API标准委员会的想法！）

(On a side note, what the hell was the standard committee thinking when they defined the API for binary_search!!!)

编辑：在这里我主要担心的是，我需要一个二进制搜索的速度，所以虽然我可以找到与其他算法的数据，如下所述，我想利用我的资料已经排序以获得二进制搜索的好处，而不只是任何搜索

My main concern here is that I need the speed of a binary search, so although I can find the data with other algorithms, as mentioned below, I want to take advantage that my data is already sorted to get the benefits of a binary search, not just any search.

到目前为止LOWER_BOUND和UPPER_BOUND失败，因为如果数据丢失：

so far lower_bound and upper_bound fail, because if the datum is missing:

//lousy pseudo code
vector(1,2,3,4,6,7,8,9,0) //notice no 5
iter = lower_bound_or_upper_bound(start,end,5)
iter != 5 && iter !=end //not returning end as usual, instead it'll return 4 or 6

此外，我真怀疑LOWER_BOUND和UPPER_BOUND实现为binary_searches，因为他们的工作一样好未排序的数据，有没有办法提供，通过参数或政策信息。 确定首先由vividos提到，他们需要排序的数据，这意味着它们是二进制搜索，所以这个世界和好如初：）的

注意：我也蛮好用一种算法，不属于std命名空间只要其与​​集装箱兼容。喜欢说的boost ::或binary_search的东西

Note: I'm also fine using an algorithm that doesn't belong to the std namespace as long as its compatible with containers. Likes say boost::binary_search or something

推荐答案

有没有这样的功能，但可以使用的 的std :: LOWER_BOUND ，的 的std :: UPPER_BOUND 或std::equal_range.

There is no such functions, but you can write a simple one using std::lower_bound, std::upper_bound or std::equal_range.

一个简单的实现可能是

template<class Iter, class T>
Iter binary_find(Iter begin, Iter end, T val)
{
    // Finds the lower bound in at most log(last - first) + 1 comparisons
    Iter i = std::lower_bound(begin, end, val);

    if (i != end && !(val < *i))
        return i; // found
    else
        return end; // not found
}

另一种解决方案是使用的std ::设为，这保证了元素的顺序，并提供了一​​种方法的迭代器查找（T键）返回一个迭代器给定的项目。但是，（如果你需要存储相同的元素多次为例）你的要求可能与使用一组兼容。

Another solution would be to use a std::set, which guarantees the ordering of the elements and provides a method iterator find(T key) that returns an iterator to the given item. However, your requirements might not be compatible with the use of a set (for example if you need to store the same element multiple times).