How to Implement an Iterator-Based Binary Search Algorithm for Sorted C Containers?

Binary Search Algorithm with Iterator Return for C Containers

The STL's std::binary_search algorithm efficiently identifies the presence of an element within a sorted container, but it only returns a boolean value. For scenarios where the exact location of the element is crucial, you may require an iterator-based search algorithm.

To address this need, the following custom binary search algorithm can be employed:

<code class="cpp">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 &amp;&amp; !(val < *i))
        return i; // found
    else
        return end; // not found
}</code>

This algorithm utilizes std::lower_bound to find the insertion point of the value in the container (if it were to be inserted). If the value is present, the iterator is returned; otherwise, the end iterator is returned. This approach ensures both speed and precision

You can also consider using a std::set, which provides an iterator find(T key) function that directly returns the iterator pointing to the given item. However, this may not be suitable for cases where duplicate elements are required.

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