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Data Structures Using C++ 2E

Data Structures Using C++ 2E. Chapter 4 Standard Template Library (STL) I. Objectives. Learn about the Standard Template Library (STL) Become familiar with the three basic components of the STL: containers, iterators , and algorithms (in Chapter 13)

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Data Structures Using C++ 2E

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  1. Data Structures Using C++ 2E Chapter 4 Standard Template Library (STL) I

  2. Objectives • Learn about the Standard Template Library (STL) • Become familiar with the three basic components of the STL: containers, iterators, and algorithms (in Chapter 13) • Explore how vector and deque containers are used to manipulate data in a program • Discover the use of iterators Data Structures Using C++ 2E

  3. Components of the STL • Program’s main objective is to manipulate data and generate results • Requires ability to store data, access data, and manipulate data • STL components • Containers • Iterators: step through container elements • Algorithms: manipulate data (e.g. sorting, search) • Containers and iterators • Class templates (types as class arguments) Data Structures Using C++ 2E

  4. Container Types • STL containers categories • Sequence containers (sequential containers) • Associative containers • Container adapters Data Structures Using C++ 2E

  5. Container Types • STL containers categories • Sequence containers (sequential containers) • vector, deque, list… • Associative containers • set, map, multiset, multimap… • Container adapters: adaptation of sequence or associative class containers by modifying and restricting its interface for some special purpose. • stack (LIFO), queue (FIFO), priority_queue… Data Structures Using C++ 2E

  6. TABLE 13-6 Containers, their associated header files, and the type of iterator supported by each container Containers, Associated Header Files,and Iterator Support Data Structures Using C++ 2E

  7. STL containers From http://cs.brown.edu/~jak/proglang/cpp/stltut/tut.html

  8. STL: Sequence containers • Contiguous blocks of objects; elements can be inserted at any point in the sequence; sequences are indexed by integers • Vector • Fast insertion at end, and allow random access. • List • Fast insertion anywhere, but provide only sequential access. • Deque • Fast insertion at either end, and allow random access. Data Structures Using C++ 2E

  9. STL: Associative containers • Associative containers are a generalization of sequences; can be indexed by any type (e.g., an ID or a name) • Implemented with a data structure called binary search tree, which will be covered later in this course. Data Structures Using C++ 2E

  10. STL: Associated containers • Sets: add, delete, search, and iterate through the set. • Multisets: Multisets are just like sets, except that duplicate copies of the same element are allowed. • Maps: Maps represent a mapping from one type (the key type) to another type (the value type). You can associate a value with a key, or find the value associated with a key, very efficiently; you can also iterate through all the keys. • Multimaps: are just like maps except that there is no limit on elemenets with the same key. Data Structures Using C++ 2E

  11. Sequence Containers • Every object has a specific position • Predefined sequence containers • vector , deque , list • Sequence container vector • Logically: same as arrays • Processed like arrays • All containers • Use same names (e.g. push_back()) for common operations • May have specific operations Data Structures Using C++ 2E

  12. Arrays • Static arrays int foo[100]; • Dynamic arrays Data Structures Using C++ 2E

  13. Sequence Container: vector • Vector container • Stores, manages objects in a dynamic array • Elements accessed randomly • Time-consuming item insertion: middle, beginning • Fast item insertion: end • Class implementing vector container • vector • Header file containing the class vector • vector Data Structures Using C++ 2E

  14. Sequence Container: vector (cont’d.) • Using a vector container in a program requires the following statement: • #include <vector> • Defining a vector container object • Specify object type • Example: vector<int> intlist; • Example: vector<string> stringList; Data Structures Using C++ 2E

  15. TABLE 4-1 Various ways to declare and initialize a vector container Sequence Container: vector (cont’d.) • Declaring vector objects Data Structures Using C++ 2E

  16. Declare and initialize a vector Data Structures Using C++ 2E

  17. Sequence Container: vector (cont’d.) • Manipulating data stored in a vector sequence container • Basic operations • Item insertion • Item deletion • Stepping through the elements of a vector array Data Structures Using C++ 2E

  18. Sequence Container: vector (cont’d.) Data Structures Using C++ 2E

  19. Access a vector Data Structures Using C++ 2E

  20. Sequence Container: vector (cont’d.) • class vector • Provides various operations to process vector container elements • Iterator • The argument position in STL terminology Data Structures Using C++ 2E

  21. TABLE 4-3 Various operations on a vector container Sequence Container: vector (cont’d.) Data Structures Using C++ 2E

  22. TABLE 4-3 Various operations on a vector container (cont’d.) Sequence Container: vector (cont’d.) Data Structures Using C++ 2E

  23. Vector: size vs. capacity • Size: the number of elements you have used. • Capacity: allocated space. In STL, it’s doubled each time if additional space is needed. Data Structures Using C++ 2E

  24. Sequence Container: vector (cont’d.) • Function push_back • Adds element to end of container • Used when declaring vector container • Specific size unknown Data Structures Using C++ 2E

  25. Iterators • Iterators provide a way of specifying a position in a container. • The code vector<int> v; // add some integers to v vector::iterator i1 = v.begin(); vector::iterator i2 = v.end(); will create two iterators like this: Data Structures Using C++ 2E

  26. Declaring an Iterator to a Vector Container • Process vector container like an array • Using array subscripting operator • Process vector container elements • Using an iterator • class vector: function insert • Insert element at a specific vector container position • Uses an iterator • class vector: function erase • Remove element • Uses an iterator Data Structures Using C++ 2E

  27. Declaring an Iterator to a Vector Container (cont’d.) • class vector contains iterator (a typedef inside the class vector) • Declared as a public member • Vector container iterator • Declared using typedef iterator • Example vector<int>::iterator intVecIter; Data Structures Using C++ 2E

  28. Declaring an Iterator to a Vector Container (cont’d.) • Requirements for using typedef iterator • Container name (vector) • Container element type • Scope resolution operator • ++intVecIter • Advances iterator intVecIter to next element into the container • *intVecIter • Returns element at current iterator position Data Structures Using C++ 2E

  29. Declaring an Iterator to a Vector Container (cont’d.) • Using an iterator into a vector container • Manipulating element type to be int Data Structures Using C++ 2E

  30. Containers and the Functions begin and end • begin() • Returns position of the first element into the container • end() • Returns position of the last element into the container • Functions have no parameters • class vector • Contains member functions used to find number of elements currently in the container Data Structures Using C++ 2E

  31. Example 4-4 Data Structures Using C++ 2E

  32. TABLE 4-4 Functions to determine the size of a vector container Containers and the Functions begin and end (cont’d.) Data Structures Using C++ 2E

  33. Member Functions Common to All Containers • Examples • Default constructor • Several constructors with parameters • Destructor • insert(), erase(), begin(), end(), etc… • Class encapsulates data, operations on that data • Into a single unit • Every container is a class • Several operations directly defined for a container • Provided as part of class definition Data Structures Using C++ 2E

  34. TABLE 4-5 Member functions common to all containers Data Structures Using C++ 2E

  35. TABLE 4-6 Member functions common to all sequence containers Member Functions Common to Sequence Containers Data Structures Using C++ 2E

  36. The copy Algorithm • Provides convenient way to output container elements • Generic STL algorithm • Usable with any container type and arrays • Does more than output container elements • Allows copying of elements from one place to another • Function template copy definition • Contained in header file algorithm Data Structures Using C++ 2E

  37. copy examples

  38. Sequence Container: deque • Deque: double-ended queue • Implemented as dynamic arrays • Can expand in either direction • Class name defining deque container • deque • Header file deque contains • Definition of the class deque • Functions to implement various operations on a deque object • Class deque contains several constructors Data Structures Using C++ 2E

  39. TABLE 4-7 Various ways to declare a deque object Sequence Container: deque (cont’d.) Data Structures Using C++ 2E

  40. TABLE 4-8 Various operations that can be performed on a deque object Sequence Container: deque (cont’d.) Data Structures Using C++ 2E

  41. Iterators • Work like pointers • Point to elements of a container (sequence or associative) • Allow successive access to each container element • Two most common operations on iterators • ++ (increment operator) • * (dereferencing operator) • Examples ++cntItr; *cntItr; Data Structures Using C++ 2E

  42. Types of Iterators • Input iterators • Output iterators • Forward iterators • Bidirectional iterators • Random access iterators Data Structures Using C++ 2E

  43. Operations supported by the iterators write access; step forward *outputIter = t; ++outputIter; Read access; step forward int t = *inputIter; ++inputIter; Both read/write; step forward Both read/write; step forward and backward. Supported in list, set, map, multiset, multimap Both read/write; jump forward and backward. rIterator = rIterator + n; Supported in vector deque, string, array

  44. Input Iterators • Read access • Step forward element-by-element • Return values element-by-element • Provided for reading data from an input stream Data Structures Using C++ 2E

  45. TABLE 4-9 Operations on an input iterator Input Iterators (cont’d.) Data Structures Using C++ 2E

  46. Output Iterators • Write access • Step forward element-by-element • Used for writing data to an output stream • Cannot be used to iterate over a range twice Data Structures Using C++ 2E

  47. TABLE 4-10 Operations on an output iterator Output Iterators (cont’d.) Data Structures Using C++ 2E

  48. Forward Iterators • Combination of • All of input iterators functionality and almost all output iterators functionality • Can refer to same element in same collection • Can process same element more than once Data Structures Using C++ 2E

  49. TABLE 4-11 Operations on a forward iterator Forward Iterators (cont’d.) Data Structures Using C++ 2E

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