The Standard Library Containers

Containers and iterators in C++

The C++ standard library offers a set of very useful container types. A container is a data structure that contains a collection of elements. The container manages the memory of the elements it holds. This means that we don't have to explicitly create and delete the objects that we put in a container. We can pass objects created on the stack to a container and the container will copy and store them on the free store.

Iterators are used to access elements in containers, and are, therefore, a fundamental concept for understanding algorithms and data structures from the standard library. It's enough to know that an iterator can be thought of as a pointer to an element and that iterators have different operators defined depending on the container they belong to. For example, array-like data structures provide random access iterators to their elements. These iterators support arithmetic expressions using + and -, whereas an iterator to a linked list, for example, only supports ++ and -- operators.

The containers are divided into three categories: