Download Basic ADTs in STL

Basic ADTs in STL
What are ADTs,
STL Intro, vector, list, queue, stack
Telerik Software Academy
Learning & Development Team
http://academy.telerik.com
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, queue
2
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 contains
a 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
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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
head
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next
next
next
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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
 Statically (using array)
 Dynamically (using pointers)
ways
Standard Template Library
Introduction, 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 Introduction
Live Demo
STL Iterators
Mechanism 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 Containers
Fast 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 Containers
Vector, 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
#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 size and is obtained by calling
vector<int> numbers;
numbers.push_back(42);
numbers.push_back(13);
cout<<numbers.size(); //prints 2
size()
STL Vector
 Accessing vector elements
 Done the same way as with arrays, i.e. []
vector<int> numbers;
numbers.push_back(42);
numbers.push_back(13);
cout<<numbers[1]; //prints 13
cout<<endl;
numbers[1] = numbers[0];
cout<<numbers[1]; //prints 42
 Traversing a vector is the same as traversing an
array (e.g. with a for loop)
 Element access does not depend on vector size
STL vector
Live Demo
STL (Linked) List
 List (#include
<list>)
 Defined: template <class T> list
 Sequence, Reversible
 Stores a sequence of elements in a doublylinked 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<int> numbers;
numbers.push_back(2);
numbers.push_front(1);
numbers.push_back(3);
 List size and is obtained by calling
size()
 List elements can be removed from front and
back fast
numbers.pop_front();
numbers.pop_back();
STL (Linked) List
 Accessing list
elements
 front and back methods provide first and last
element access
cout<<numbers.front();
cout<<numbers.back();
 Only way to get access to all elements –
traversal by iterator
list<int>::iterator numbersIterator;
for(numbersIterator = numbers.begin();
numbersIterator != numbers.end();
numbersIterator++)
{
cout<<*numbersIterator<<endl;
}
STL list
Live 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 back
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STL Queue
 Declaring and initializing
a queue
queue<int> q;
q.push(1);
q.push(2);
q.push(3);
 Queue size is obtained by calling
 Queues allow
size()
removing elements only from
the front of the sequence
q.pop();
STL Queue
 Accessing
queue elements
 front and back methods provide first and last
element access
cout<<q.front();
cout<<q.back();
 Other types of access to queue elements are
meaningless
 The idea of the queue is to restrict access and be
FIFO
STL queue
Live 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<int> s;
s.push(1);
s.push(2);
s.push(3);
 Stack size is obtained by calling
 Stacks allow
size()
removing elements only from the
back (top) of the sequence
s.pop();
STL Stack
 Accessing
stack elements
 top method provides first element access
cout<<s.top();
 Other types of access to stack elements are
meaningless
 The idea of the stack is to restrict access and be
LIFO
STL stack
Live Demo
Basic ADTs in STL
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Exercises
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