Leverage Existing Algorithms: Gather
Explore how to implement the gather algorithm using C++20 STL features and the stable_partition algorithm. Understand how to move elements that meet a predicate about a pivot in containers like vectors or strings. This lesson helps you leverage existing STL algorithms to manipulate data efficiently with iterator-based techniques.
We'll cover the following...
gather() is an example of an algorithm that leverages existing algorithms. The gather() algorithm takes a pair of container iterators and moves the elements that satisfy a predicate toward a pivot position within the sequence, returning a pair of iterators that contains the elements that satisfy the predicate.
For example, we could use a gather algorithm to sort all the even numbers to the mid-point of a vector:
vector<int> vint{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };gather(vint.begin(), vint.end(), mid(vint), is_even);for(const auto& el : vint) cout << el;
Our output is:
1302468579
Note: The even numbers are all in the middle of the output.
In this recipe, we will implement a gather algorithm using ...