Basic ADTs in STLWhat are ADTs,

STL Intro, vector, list, queue, stack

Learning & Development Teamhttp://academy.telerik.com

Telerik Software Academy

Table of Contents

1. Basic Abstract Data Types

1.List

2.Linked List

3.Stack

4.Queue

2. ADTs in STL

1.STL Intro

2.Iterators

3.Vector, list, stack, queue2

Abstract Data Types

Basic Data Structures

Abstract Data Types An Abstract Data Type (ADT) is a data type together with the operations, whose properties are specified independently of any particular implementation

ADT are set of definitions of operations Can have several different implementations Different implementations can have different efficiency

Basic Data Structures Linear structures

Lists: fixed size and variable size Stacks: LIFO (Last In First Out) structure Queues: FIFO (First In First Out) structure

Trees Binary, ordered, balanced, etc.

Dictionaries (maps) Contain pairs (key, value) Hash tables: use hash functions to search/insert

Lists

The List ADT Data structure (container) that containsa sequence of elements Can have variable size Elements are arranged linearly, in sequence

Can be implemented in several ways Statically (using array fixed size) Dynamically (linked implementation) Using resizable array

Static List Implemented by an array

Direct access by index (fast) Insertion and deletion and resizing

are slow operations

L 2 18 7 1

2 3 6 11 9

0 1 2 3 4 5 6 7

Linked List Dynamic (pointer-based) implementation

Direct access to first/last element No access by index

go through all previous elements (slow)

Insertion and deletion are fast Resizing – add new element at the end or beginning

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Stacks

The Stack ADT LIFO (Last In First Out) structure Elements inserted (push) at “top” Elements removed (pop) from “top” Useful in many situations

E.g. the execution stack of the program Can be implemented in several ways

Statically (using array) Dynamically (linked implementation)

Queues

The Queue ADT FIFO (First In First Out) structure Elements inserted at the tail (Enqueue)

Elements removed from the head (Dequeue)

Useful in many situations Print queues, message queues, etc.

Can be implemented in several ways Statically (using array) Dynamically (using pointers)

Standard Template LibraryIntroduction, Basic ADT

Implementations

STL Introduction Standard Template Library

C++ Library

Implements a lot of computer science fundamentals Container classes, Algorithms

Iterators

Mostly template-based

Algorithms decoupled from containers through iterators

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STL Introduction Containers

Data structures, hold collections of elements

Different benefits and downsides

Implement fundamental Abstract Data Types Sequence, Associative, String,

Adaptors…

Iterators Provide access to container

elements

Used to "traverse" containers

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STL Introduction Algorithms

Fundamental algorithms over collections or single

Hook up with iterators to access container elements

Function objects Wrap functions/methods into

objects

Implement () operator – called like functions

Called by algorithms and containers to act over elements (elements passed as parameters)

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STL IntroductionLive Demo

STL IteratorsMechanism for traversing container

elements

STL Iterators "Smart" pointers to objects Specific for each container type

Each container defines how it’s iterators work

If we have an iterator to one element Increase/decrease it to get the

other elements

Types: Input, Output

Forward iterator, Bidirectional iterator

Random access iterator

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STL ContainersFast data structures to store elements

STL Containers Store collections of other objects Has methods to access elements Types

By traversability: Forward – elements ordered, Forward

Iterators

Reversible – have Bidirectional iterators

Random access – have Random access iterators

By storage: sequence, adaptors, associative

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Basic STL ContainersVector, List, Deque, Queue, Stack

STL Vector Vector (#include <vector>)

Defined: template <class T> vector

Sequence, Random Access

Stores a sequence of elements in contiguous memory

Manages memory effectively

Fast at retrieving elements by index and adding elements at the end

Slow insertion/deletion in middle or beginning

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STL Vector Declaring and initializing a vector

Vector size and is obtained by calling size()

#include<vector> //required header…vector<int> numbers;numbers.push_back(42); //numbers is now {42}numbers.push_back(13); //numbers is now {42, 13}int consoleNumber; cin>>consoleNumber;numbers.push_back(consoleNumber)

vector<int> numbers;numbers.push_back(42);numbers.push_back(13);cout<<numbers.size(); //prints 2

STL Vector Accessing vector elements

Done the same way as with arrays, i.e. []

Traversing a vector is the same as traversing an array (e.g. with a for loop)

Element access does not depend on vector size

vector<int> numbers;numbers.push_back(42);numbers.push_back(13);cout<<numbers[1]; //prints 13cout<<endl;numbers[1] = numbers[0];cout<<numbers[1]; //prints 42

STL vectorLive Demo

STL (Linked) List List (#include <list>)

Defined: template <class T> list

Sequence, Reversible

Stores a sequence of elements in a doubly-linked list

Fast at deletion/insertion anywhere

No random access to elements Have to traverse list to get to an

item

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STL (Linked) List Declaring and initializing a list

List size and is obtained by calling size()

List elements can be removed from front and back fast

list<int> numbers;

numbers.push_back(2);numbers.push_front(1);numbers.push_back(3);

numbers.pop_front();numbers.pop_back();

STL (Linked) List Accessing list elements

front and back methods provide first and last element access

Only way to get access to all elements – traversal by iterator

cout<<numbers.front();cout<<numbers.back();

list<int>::iterator numbersIterator;for(numbersIterator = numbers.begin(); numbersIterator != numbers.end(); numbersIterator++){ cout<<*numbersIterator<<endl;}

STL listLive Demo

STL Queue Queue (#include<queue>)

Defined: template <class T> queue

Sequence Adaptor

First in, First out structure (FIFO)

Stores a sequence of elements

Provides access only to first element

Can remove only at front

Can add only at back32

STL Queue Declaring and initializing a queue

Queue size is obtained by calling size()

Queues allow removing elements only from the front of the sequence

queue<int> q;

q.push(1);q.push(2);q.push(3);

q.pop();

STL Queue Accessing queue elements

front and back methods provide first and last element access

Other types of access to queue elements are meaningless

The idea of the queue is to restrict access and be FIFO

cout<<q.front();cout<<q.back();

STL queueLive Demo

STL Stack Stack (#include <stack>)

Defined: template <class T> stack

Sequence adaptor

Last in, First out structure (LIFO)

Stores a sequence of elements

Provides access only to last element

Can remove or add elements only at back/top

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STL Stack Declaring and initializing a stack

Stack size is obtained by calling size()

Stacks allow removing elements only from the back (top) of the sequence

stack<int> s;

s.push(1);s.push(2);s.push(3);

s.pop();

STL Stack Accessing stack elements

top method provides first element access

Other types of access to stack elements are meaningless

The idea of the stack is to restrict access and be LIFO

cout<<s.top();

STL stackLive Demo

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Basic ADTs in STL

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Exercises

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