Chapter 22 STL Containers §22.1 STL Basics §22.2 STL Iterators §22.3 Sequence Containers §22.4 Associative Containers §22.5 Container Adapters

§22.1 STL Basics  Standard Template Library (STL) 标准模板库 A software library included in the C++ Standard Library  Purpose To standardize commonly used components  History Originally developed by Alexander Stepanov in 1980sAlexander Stepanov Accepted as part of C++ standard in Feb

Three Components of STL  Containers （容器） A container object, such as vector, used to store a collection of data, often referred to as elements  Iterators （迭代器） Objects that facilitate traversing through the elements in a container Like built-in pointers that provide a convenient way to access and manipulate the elements in a container  Algorithms （算法） Functions to manipulate data such as sorting, searching, and comparing elements. Most of them use iterators to access the elements in the container. 3

Three Types of Containers  Sequence/sequential containers, 序列容器 Represent linear data structures Three sequence containers  vector 向量, list 表, and deque 双端队列  Associative containers, 关联容器 / 联合容器 Non-linear containers that can locate elements stored in the container quickly Four associative containers  set 集合, multiset 多重集合, map 映射, and multimap 多重映射  Container adapters ，容器适配器 Constrained versions of sequence containers stack 栈, queue 队列, and priority_queue 优先队列 4

Container Classes 5

Common Functions to All Containers 6

Common Functions to Sequence/Associative Containers 7

Simple Demo Listing 22.1 gives a simple example that demonstrates how to create a vector, list, deque, set, multiset, stack, and queue. 8 SimpleSTLDemo

§22.2 STL Iterators  Iterators are objects to facilitate traversing through the elements in a container  A iterator is like a built-in pointer that can manipulate the elements in a container 9 IteratorDemo Pointers themselves are iterators. The array pointers can be treated as iterators.

Type of Iterators  Different containers may have different types of iterators  Five types: Input (Output) iterator  For reading/writing from/to container  Moving only in forward direction Forward iterator  Combination of input/output iterator Bidirectional iterator  A forward iterator that can move backward Random access iterator  A bidirectional iterator that can jump 10

Iterator Types Supported by Containers 11

Predefined Iterators  Iterators have been defined in every containers Using “typedef”  The typedefs of iterators iterator const_iterator reverse_iterator const_reverse_iterator 12 typedef int integer; integer value = 40; ReverseIteratorDemo ConstIteratorDemo

Iterator Operators  Using overloaded operators to manipulate the an iterator Move its position Access the element Compare with other iterators 13

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Iterator Operator Demo 15 IteratorOperatorDemo vector intVector; intVector.push_back(10); intVector.push_back(20); intVector.push_back(30); intVector.push_back(40); intVector.push_back(50); intVector.push_back(60); vector ::iterator p1 = intVector.begin(); for (; p1 != intVector.end(); p1++){ cout << *p1 << " "; } cout << endl << *(--p1) << endl; cout << *(p1 - 3) << endl; cout << p1[-3] << endl; *p1 = 1234; cout << *p1 << endl;

I/O Steam Iterators  Iterators can also be used to manipulate I/O streams input iterator and output iterator 16 InputOutputStreamIteratorDemo

§22.3 Sequence Containers  Represent linear data structures 17 Header file Strong pointsWeak pointsImpl. struct. vector Random access Inserting and deleting at the end Inserting/Deleting in the middle or front array deque Random access Inserting and deleting at the front and end Inserting/Deleting in the middle array list Inserting and deleting anywhere Random accesslinkedlist

Common Functions in Sequence Container 18

Sequence Container: vector 19 VectorDemo An insert call may invalidate previously obtained iterators!

Sequence Container: deque 20 DequeDemo An insert call may invalidate previously obtained iterators!

Sequence Container: list 21 ListDemo An insert call won’t change the previously obtained iterators!

§22.4 Associative Containers  Represent non-linear data structures Elements in an associative container are sorted according to some sorting criterion (“<” by default)  For fast storage and quick retrieval using keys 22 Header file Strong pointsWeak pointsImpl. struct. set mutlset For fast storage and quick retrieval using keys Inserting/DeletingBST map multimap For fast storage and quick retrieval using keys Inserting/DeletingBST

Common Functions in Associative Containers 23

Associative Containers: set and multiset  Mathematical set to store simple elements  set and multiset are identical except that multiset allows duplicate keys 24 SetDemo

Associative Containers: map and multimap  Storage of mapping from one data item (a key) to another (a value).  map and multimap are identical except that multimap allows duplicate keys 25 MapDemo

§22.5 Container Adapters  Containers adapted from the sequence containers For handling special cases  Programmer can choose an appropriate sequence container for a container adapter 26 Header file FeaturesImpl. struct. stack Last-In-First-Outdeque*, list, vector queue First-In-First-Outdeque*, list priority_queue Largest-In-First-Outvector*, deque *: default one

Container Adapter: stack 27 StackDemo

Container Adapter: queue 28 QueueDemo

Container Adapter: priority_queue 29 PriorityQueueDemo

A Summary  Concepts STL, Container, Iterator, Algorithm Three types of containers  Features of different containers  Syntax of declaring container objects  Main functions of containers 30