C++ STL Containers: When to Use Vector, Map, Set Instead of Arrays

Developer Alan Wu shares a practical guide on choosing the right C++ Standard Template Library containers over plain arrays. Vectors are recommended for ordered lists that grow dynamically, replacing fixed-size arrays that risk overflow and require manual length tracking. For key-value lookups, unordered_map offers O(1) average performance, while map is preferred when sorted key order matters. To track unique values, set and unordered_set outperform looping through a vector each time. Wu argues that matching the right container to the use case eliminates unnecessary complexity and covers roughly 90% of common programming scenarios.