Containers in C++ STL

The C++ STL (Standard Template Library) is a powerful set of C++ template classes to provide general-purpose classes and functions with templates that implement many popular and commonly used algorithms and data structures like vectors, lists, queues, and stacks.

It is a library of container classes, algorithms, and iterators. It is a generalized library and so, its components are parameterized. Working knowledge of template classes is a prerequisite for working with STL.

Templates are a feature of the C++ programming language that allows functions and classes to operate with generic types. This allows a function or class to work on many different data types without being rewritten for each one

C++ Standard Template Library has following three well-structured components −

1 Containers

Containers are used to manage collections of objects of a certain kind. There are several different types of containers like deque, list, vector, map, etc.

• Sequence Containers - These containers implement data structures which can be accessed in a sequential manner.

  • vector
  • list
  • deque
  • arrays
  • forward_list

• Container Adaptors - They provide a different interface for sequential containers.

  • queue
  • priority_queue
  • stack

• Associative Containers - They implement sorted data structures that can be quickly searched (O(log n) complexity).

  • set
  • multiset
  • map
  • multimap

• Unordered Associative Containers - These containers implement unordered data structures that can be quickly searched

  • unordered_set
  • unordered_multiset
  • unordered_map
  • unordered_multimap

2 Algorithms

Algorithms act on containers. They provide the means by which you will perform initialization, sorting, searching, and transforming the contents of containers.

Algorithm

• Sorting
• Searching
• Important STL Algorithms
• Useful Array algorithms
• Partition Operations

3 Iterators

Iterators are used to step through the elements of collections of objects. These collections may be containers or subsets of containers.