15 Different Ways to Filter Containers in Modern C++ -- Bartłomiej Filipek
Filtering items from a container is a common situation. Bartłomiej Filipek demonstrates various approaches from different versions of C++.
15 Different Ways to Filter Containers in Modern C++
by Bartłomiej Filipek
From the article:
Do you know how many ways we can implement a filter function in C++? While the problem is relatively easy to understand – take a container, copy elements that match a predicate and the return a new container – it’s good to exercise with the C++ Standard Library and check a few ideas. We can also apply some modern C++ techniques, including C++23. Let’s start!
The problem statement
To be precise by a filter, I mean a function with the following interface:
auto Filter(const Container& cont, UnaryPredicate p) {}It takes a container and a predicate, and then it creates an output container with elements that satisfy the predicate. We can use it like the following:
const std::vector<std::string> vec{ "Hello", "**txt", "World", "error", "warning", "C++", "****" }; auto filtered = Filter(vec, [](auto& elem) { return !elem.starts_with('*'); }); // filtered should have "Hello", "World", // "error", "warning", "C++"Writing such a function can be a good exercise with various options and algorithms in the Standard Library. What’s more, our function hides internal things like iterators, so it’s more like a range-based version.
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