What is the difference between std::vector and std::array?

Question

Accepted Answer

**std::vector:** - Dynamic size (heap allocated) - Can grow/shrink - Pointer invalidation on reallocation - Slight overhead for size tracking ```cpp std::vector v = {1, 2, 3}; v.push_back(4); // grows dynamically ``` **std::array:** - Fixed size (stack allocated) - Compile-time constant size - No allocation overhead - Better cache locality ```cpp std::array arr = {1, 2, 3, 4, 5}; // arr.size() is constexpr ``` **When to use:** - Use `std::array` when size is known at compile time - Use `std::vector` when size varies - Use `std::array` for small, fixed collections - Use `std::vector` as default container

C++: What is the difference between std::vector and std::array?