Lesson 33: Algorithms (sort, find, transform, etc.)

Algorithms (sort, find, transform, etc.)\n\nThe <algorithm> header provides a wealth of generic algorithms that operate on iterator ranges. They are designed to work with any container that supplies the appropriate iterator category.\n\n---\n\n## Commonly used algorithms\n- Sorting – std::sort, std::stable_sort, std::partial_sort.\n- Searching – std::find, std::binary_search, std::lower_bound, std::upper_bound.\n- Modification – std::transform, std::replace, std::remove, std::unique.\n- Numeric – std::accumulate, std::inner_product, std::reduce (C++17).\n\n---\n\n## Example: Sorting a vector of structs by a member field\ncpp\nstruct Person {\n std::string name;\n int age;\n};\nstd::vector<Person> people = { {\"Bob\",30}, {\"Alice\",25}, {\"Eve\",35} };\n// Sort by age ascending using a lambda comparator\nstd::sort(people.begin(), people.end(), [](const Person& a, const Person& b) {\n return a.age < b.age;\n});\nfor (const auto& p : people) {\n std::cout << p.name << \" (\" << p.age << \")\\n\";\n}\n\n\n> Tip: When possible, use the range‑based overloads from <algorithm> (C++20) like std::ranges::sort for clearer syntax.\n\n---\n\n<Alert type="info">Many algorithms invalidate iterators after they modify the container (e.g., std::remove does not actually erase elements). Pair them with vector::erase when needed.