C++ Programming: Program Design Including Data Structures, Fifth Edition

1. C++ Programming:Program Design IncludingData Structures, Fifth Edition Chapter 22: Standard Template Library (STL)

2. Objectives In this chapter, you will: • Learn about the Standard Template Library (STL) • Become familiar with the basic components of the STL: containers, iterators, and algorithms • Explore how various containers are used to manipulate data in a program • Discover the use of iterators • Learn about various generic algorithms C++ Programming: Program Design Including Data Structures, Fifth Edition

3. Introduction • ANSI/ISO Standard C++ is equipped with a Standard Template Library (STL) • The STL provides class templates to process lists, stacks, and queues • This chapter: • Discusses many important features of the STL • Shows how to use its tools C++ Programming: Program Design Including Data Structures, Fifth Edition

4. Components of the STL • Components of the STL: • Containers • Iterators • Algorithms • Containers and iterators are class templates • Iterators are used to step through the elements of a container • Algorithms are used to manipulate data C++ Programming: Program Design Including Data Structures, Fifth Edition

5. Container Types • Manage objects of a given type • Three categories: • Sequence (sequential) containers • Associative containers • Container adapters C++ Programming: Program Design Including Data Structures, Fifth Edition

6. Sequence Containers • Every object has a specific position • Three predefined sequence containers: • vector • deque • list C++ Programming: Program Design Including Data Structures, Fifth Edition

7. Sequence Container: vector • Stores and manages its objects in a dynamic array • Must have: #include <vector> • To define an object of type vector, specify the type of the object • Examples: vector<int> intList; vector<string> stringList; • vector contains several constructors C++ Programming: Program Design Including Data Structures, Fifth Edition

8. Sequence Container: vector (cont'd.) • Basic vector operations: • Item insertion and deletion • Stepping through the elements C++ Programming: Program Design Including Data Structures, Fifth Edition

9. Sequence Container: vector (cont'd.) C++ Programming: Program Design Including Data Structures, Fifth Edition

10. Sequence Container: vector (cont'd.) C++ Programming: Program Design Including Data Structures, Fifth Edition

11. Sequence Container: vector (cont'd.) C++ Programming: Program Design Including Data Structures, Fifth Edition

12. Declaring an Iterator to a Vector Container • A vector contains a typedefiterator • For example, the statement vector<int>::iteratorintVecIter; declares intVecIter to be an iterator into a vector container of type int • ++intVecIter • Advances the iterator • *intVecIter • Returns element at current iterator position C++ Programming: Program Design Including Data Structures, Fifth Edition

13. Containers and the Functions begin and end • Every container contains the member function begin and end • begin returns the position of the first element • end returns the position of the last element • Both functions have no parameters C++ Programming: Program Design Including Data Structures, Fifth Edition

14. Member Functions Common to All Containers C++ Programming: Program Design Including Data Structures, Fifth Edition

15. Member Functions Common to All Containers (cont'd.) C++ Programming: Program Design Including Data Structures, Fifth Edition

16. Member Functions Common to All Containers (cont'd.) C++ Programming: Program Design Including Data Structures, Fifth Edition

17. Member Functions Common to Sequence Containers C++ Programming: Program Design Including Data Structures, Fifth Edition

18. Member Functions Common to Sequence Containers (cont'd.) C++ Programming: Program Design Including Data Structures, Fifth Edition

19. The copy Algorithm • Function copy: convenient way to output the elements of a container • Copies elements from one place to another • Can output the elements of a vector • Prototype: copies elements within range first1...last-1 • Must have: #include <algorithm> C++ Programming: Program Design Including Data Structures, Fifth Edition

20. The copy Algorithm (cont'd.) • Example: int intArray[] = {5, 6, 8, 3, 40, 36, 98, 29, 75}; vector<int> vecList(9); copy(intArray, intArray + 9, vecList.begin()); • After the previous statement executes: vecList = {5, 6, 8, 3, 40, 36, 98, 29, 75} C++ Programming: Program Design Including Data Structures, Fifth Edition

21. The copy Algorithm (cont'd.) • Consider the statement : copy(intArray + 1, intArray + 9, intArray); • After the previous statement executes: intArray = {6, 8, 3, 40, 36, 98, 29, 75, 75} • Now, consider the statement: copy(vecList.rbegin() + 2, vecList.rend(), vecList.rbegin()); • After the previous statement executes: vecList = {5, 6, 5, 6, 8, 3, 40, 36, 98} C++ Programming: Program Design Including Data Structures, Fifth Edition

22. The ostream Iterator and the Function copy • One way to output the contents of a container is to use a for loop, along with begin (initialize) and end (loop limit) • copy can output a container • An iterator of the type ostream specifies destination • When creating an iterator of the type ostream: • Specify the type of element that the iterator will output C++ Programming: Program Design Including Data Structures, Fifth Edition

23. The ostream Iterator and the Function copy (cont'd.) • Example: ostream_iterator<int> screen(cout, " "); copy(intArray, intArray + 9, screen); copy(vecList.begin(), vecList.end(), screen); • The last statement is equivalent to: copy(vecList.begin(), vecList.end(), ostream_iterator<int>(cout, " ")); • Another example: copy(vecList.begin(), vecList.end(), ostream_iterator<int>(cout, ", ")); C++ Programming: Program Design Including Data Structures, Fifth Edition

24. Sequence Container: deque • deque stands for double-ended queue • Implemented as dynamic arrays • Elements can be inserted at both ends • A deque can expand in either direction • Elements are also inserted in the middle C++ Programming: Program Design Including Data Structures, Fifth Edition

25. Sequence Container: deque(cont’d.) C++ Programming: Program Design Including Data Structures, Fifth Edition

26. Sequence Container: deque(cont’d.) C++ Programming: Program Design Including Data Structures, Fifth Edition

27. Sequence Container: list • Lists are implemented as doubly linked lists • Every element in a list points to both its immediate predecessor and its immediate successor • Except the first and last element • The list is not a random access data structure C++ Programming: Program Design Including Data Structures, Fifth Edition

28. Sequence Container: list (cont'd.) C++ Programming: Program Design Including Data Structures, Fifth Edition

29. Sequence Container: list (cont'd.) C++ Programming: Program Design Including Data Structures, Fifth Edition

30. Sequence Container: list (cont'd.) C++ Programming: Program Design Including Data Structures, Fifth Edition

31. Sequence Container: list (cont'd.) C++ Programming: Program Design Including Data Structures, Fifth Edition

32. Sequence Container: list (cont'd.) C++ Programming: Program Design Including Data Structures, Fifth Edition

33. Sequence Container: list (cont'd.) C++ Programming: Program Design Including Data Structures, Fifth Edition

34. Iterators • An iterator points to the elements of a container (sequence or associative) • Iterators provide access to each element • Most common operations on iterators • ++ (increment) • * (dereference) C++ Programming: Program Design Including Data Structures, Fifth Edition

35. Types of Iterators • Input iterators: have read access; step forward element-by-element • Output iterators: have write access; step forward element-by-element • Forward iterators: have all functionality of input and almost all of output iterators • Bidirectional iterators: can go backward • Random access iterators: bidirectional iterators that can randomly process the elements of a container C++ Programming: Program Design Including Data Structures, Fifth Edition

36. Input Iterators C++ Programming: Program Design Including Data Structures, Fifth Edition

37. Output Iterators • Output iterators cannot be used to iterate over a range twice • If we write data at same position, there is no guarantee that new value will replace old one C++ Programming: Program Design Including Data Structures, Fifth Edition

38. Forward Iterators C++ Programming: Program Design Including Data Structures, Fifth Edition

39. Bidirectional Iterators • Forward iterators that can also iterate backward over the elements • The operations defined for forward iterators apply to bidirectional iterators • Use the decrement operator to step backward C++ Programming: Program Design Including Data Structures, Fifth Edition

40. Random Access Iterators • Can be used with containers of the types vector, deque, string, as well as arrays • Operations defined for bidirectional iterators apply to random access iterators C++ Programming: Program Design Including Data Structures, Fifth Edition

41. Types of Iterators (cont'd.) C++ Programming: Program Design Including Data Structures, Fifth Edition

42. typedef iterator • Every container contains a typedef iterator • The statement: vector<int>::iterator intVecIter; declares intVecIter to be an iterator into a vector container of the type int C++ Programming: Program Design Including Data Structures, Fifth Edition

43. typedef const_iterator • With the help of an iterator into a container and the dereference operator, *, you can modify the elements of the container • If the container is declared const, then we must prevent the iterator from modifying the elements • Every container contains typedefconst_iterator to handle these situations C++ Programming: Program Design Including Data Structures, Fifth Edition

44. typedef reverse_iterator • Every container also contains the typedef reverse_iterator • An iterator of this type is used to iterate through the elements of a container in reverse C++ Programming: Program Design Including Data Structures, Fifth Edition

45. typedef const_reverse_iterator • Read-only iterator • Used to iterate through the elements of a container in reverse • Required if: • The container is declared as const • Need to iterate through the elements of the container in reverse C++ Programming: Program Design Including Data Structures, Fifth Edition

46. Other typedefs Common to AllContainers C++ Programming: Program Design Including Data Structures, Fifth Edition

47. Stream Iterators • istream_iterator • Used to input data into a program from an input stream • ostream_iterator • Used to output data into an output stream C++ Programming: Program Design Including Data Structures, Fifth Edition

48. Associative Containers • Elements in an associative container are automatically sorted according to some ordering criteria • Predefined associative containers in the STL: • Sets • Multisets • Maps • Multimaps C++ Programming: Program Design Including Data Structures, Fifth Edition

49. Associative Containers: set and multiset • Associative containers set and multiset automatically sort their elements • multiset allows duplicates; set does not • The default sorting criterion is the relational operator < (less than) • Ascending order • Must #include <set> C++ Programming: Program Design Including Data Structures, Fifth Edition

50. Declaring set or multiset Associative Containers C++ Programming: Program Design Including Data Structures, Fifth Edition