Containers and the Standard Template Library (STL)

Transcription

1 Containers and the Standard Template Library (STL) Professor Hugh C. Lauer CS-2303, System Programming Concepts (Slides include materials from The C Programming Language, 2 nd edition, by Kernighan and Ritchie, Absolute C++, by Walter Savitch, The C++ Programming Language, Special Edition, by Bjarne Stroustrup, and from C: How to Program, 5 th and 6 th editions, by Deitel and Deitel) 1

2 From previous topic class BinaryTree { public: TreeNode *AddNode(const string &word); int gettotalnodes(); void PrintTree(ostream &output); BinaryTree(); //Default constructor ~BinaryTree(); //Destructor There is something else unsatisfying about this implementation. What is it? private: static int totalnodes; void PrintTree(TreeNode *subtree, ostream &output); TreeNode *AddNode(TreeNode *subtree, const string &word); TreeNode *root; }; // class BinaryTree 2

3 From previous topic class BinaryTree { public: TreeNode *AddNode(const string &word); int gettotalnodes(); void PrintTree(ostream &output); BinaryTree(); //Default constructor ~BinaryTree(); //Destructor The class TreeNode is also problem specific it has a string and a count private: static int totalnodes; void PrintTree(TreeNode *subtree, ostream &output); TreeNode *AddNode(TreeNode *subtree, const string &word); TreeNode *root; }; // class BinaryTree 3

4 Consequence It would be a fair amount of work to adapt this binary tree implementation to some other purpose E.g., managing parse trees in a language translator Managing employee records Keeping track of baseball statistics... It would be nice to have a binary tree class that would work for a wide variety of payload types 4

5 Templates to the rescue! template <class T> class TreeNode { public: friend class BinaryTree<T> friend class iterator<t> TreeNode(T data) : payload(data) {} private: T payload; TreeNode<T> *left; TreeNode<T> *right; } // template <class T> // class TreeNode template <class T> class BinaryTree { public: void insert(t item); TreeNode<T> *find(t item); // iterator methods? private: TreeNode<T> * root; void insert(t item, TreeNode<T> *subtree); TreeNode<T> *find(t item, TreeNode<T> *subtree); } // template <class T> // class BinaryTree 5

6 Result You can concentrate on building the binary tree Without worrying much about what it contains You can hand off the task of comparing nodes to the overloaded operators of <class T> You can take advantage of decades of knowledge and expertise accumulated about binary trees and other forms of search trees See Absolute C & Figs

7 The Standard Template Library (STL) A large collection of template container classes Also a bunch of other stuff Part of the C++ standard Embodies the collective wisdom and experience of the contributors 7

8 Containers in the STL Vectors Generalization of arrays Range checking Resizable All common C operators are overloaded to apply to vectors ++, --, [], ->, *, etc. Comprehensive set of iterators vector<bool> A highly optimized specialization of one-bit per element 8

9 Containers in the STL (continued) List Doubly-linked Stack Deque i.e., a double ended queue Queue All of the usual list operations, constrained to circumstances of the container Iterators specifically adapted to these containers 9

10 Containers in the STL (continued) basic_string The underlying class for string typedef basic_string<char> string Comparisons, assignments, iterators, etc. Substring, searching, pattern-matching String stream I.e., using << and >> to insert to or extract from strings instead of streams International character strings wchar, unicode, etc. 10

11 Containers in the STL (continued) map Associative array search by value set Sets of objects Usual set operators for union, intersection, etc. bitset Array of booleans 11

12 Other features in STL General utilities Date & time, memory allocators, etc. Iterators Lots of tools General algorithms Mostly for sets, partitions, sequences, binary searches, swapping, sorting, etc. Exception handling exception class, assertions, etc. Localization tools Representations of dates, currencies, numbers, etc. Numerics Numeric operations, complex, math functions, random numbers, etc. Input-output Streams, files, manipulators, etc. 12

13 Questions? 13