Introduction

Although the sequential and associative containers of the Standard Template library are two very different classes of containers, they have a lot in common. For example, the operations used to create or delete a container, to determine its size, to access its elements, to assign or swap, are all independent of the type of elements in a container. It is common for the containers to be defined with an arbitrary size. The reason is that each container has an allocator, hence the size of a container can be adjusted at runtime. The allocator works in the background most of the time. This can be seen for an std::vector. The call std::vector<int> results in a call std::vector<int, std::allocator<int>>. Because of the std::allocator we can adjust the size of all containers dynamically, except for std::array. However, they have even more in common. We can access the elements of a container quite easily with an iterator.

Having so much in common, the containers differ in their details. The chapters Sequential Containers and Associative Containers in General provide these details.

C++ covers the sequential containers std::array, std::vector, std::deque, std::list, and std::forward_list, in detail.

The same holds true for associative containers, which can be classified in the ordered and unordered associative container.