Standard Template Library in C++

Need of STL?

When we develop some applications we have to deal with data. The data is a collection of values and for storing the collection of values we need data structures. CPP provides built-in libraries of classes for all these data structures and that collection of classes are called STL (Standard Template Libraries ).

STL consists of

1. ALgorithms
2. Containers
3. Iterators

• Algorithms are the functions used to perform operations on containers
• For example :

sort()

reverse()

count()

find()

binary_search()

lower_bound()

upper_bound()

next_permutation()

prev_permutation()

distance()

• A container is a holder object that stores a collection of other objects. They are implemented as class templates, which allows great flexibility in the types supported as elements.
• The container manages the storage space for its elements and provides member functions to access them, either directly or through iterators.
• Many containers have several functions in common, and share functionalities. The decision of which type of container to use for a specific need does not generally depend only on the functionality offered by the container, but also on the efficiency of some of its members
• For example :

vector

list

forward_list

deque

priority_queue

stack

set

multiset

map

multimap

• An iterator is any object that, pointing to some element in a range of elements (such as an array or a container), has the ability to iterate through the elements of that range using a set of operators (with at least the increment (++) and dereference (*) operators).
• The most obvious form of iterator is a pointer: A pointer can point to elements in an array and can iterate through them using the increment operator (++). But other kinds of iterators are possible. For example, each container type (such as a list) has a specific iterator type designed to iterate through its elements.
• For example :

iterator

iterator_traits

reverse_iterator

move_iterator

back_insert_iterator

front_insert_iterator

insert_iterator

istream_iterator

ostream_iterator

input_iterator_tag

Example code with the definition of each container :

References :

• https://www.cplusplus.com/