1. Programming Assignment #4 Binary Trees in C++
Professor Hugh C. Lauer CS-2303, System Programming Concepts
(Slides include materials from The C Programming Language, 2nd 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, 5th and 6th editions, by Deitel and Deitel)
CS-2303, A-Term 2012
Programming Assignment #4

2. Programming Assignment #4
Write a C++ program to
Read one or more text files
Build up a binary tree of words in those text files
Print to an output file an alphabetical list of words and number of occurrences of each word
Also total number of different words
CS-2303, A-Term 2012
Programming Assignment #4

3. Programming Assignment #4
Reading
Absolute C++
Chapter 6 — structs and classes
§7.1 — constructors
§17.3 — Trees
Review Binary Trees
C lecture notes on Binary Trees
K&R §6.5
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Programming Assignment #4

4. Programming Assignment #4
This Assignment
Command line program
./PA4 outputFile inputFile1 inputFile2 ...
Open and read each input file in turn
Scan for words
Store each new word in binary tree
Increment count of words previously entered
Open and write to output
List of words
Count for each word
Total number of distinct words
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Programming Assignment #4

5. Programming Assignment #4
Example Output
166 a 25 and 11 as 3 command 15 each 2 file 4 files 109 in 4 input 98 it 1 it’s 99 of 3 open 6 program 18 read 152 the 41 this 3 under 30 would Total number of different words
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Programming Assignment #4

6. Programming Assignment #4
Notes
Upper and lower case words are the same
“This” and “this”
Related words that are spelled differently are different
“Car” vs. “cars”
Recognize apostrophes & hyphens as parts of words
“Bob’s”
“double-ended”
CS-2303, A-Term 2012
Programming Assignment #4

7. Programming Assignment #4
Guidance
Think through this problem in Java
Use as inspiration and guideline for C++ implementation
One or more class interface files (.h)
A corresponding class implementation file (.cpp) for each class interface
One or more .cpp files for main() and other non-class functions
Don’t use templates from Standard Template Library!
You must build your own classes!
CS-2303, A-Term 2012
Programming Assignment #4

8. Programming Assignment #4
Test Files
Provided in project assignment
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Programming Assignment #4

9. Programming Assignment #4
Submission
Build in Eclipse
Make clean before submitting
Export to a zip file so grader can unzip and build on Linux
Project name:– PA4
Submit zip file, README, output from test cases
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Programming Assignment #4

10. Programming Assignment #4
What is a Binary Tree?
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Programming Assignment #4

11. Programming Assignment #4
Definitions
Linked List
A data structure in which each element is dynamically allocated and in which elements point to each other to define a linear relationship
Singly- or doubly-linked
Stack, queue, circular list
Tree
A data structure in which each element is dynamically allocated and in which each element has more than one potential successor
Defines a partial order
CS-2303, A-Term 2012
Programming Assignment #4

12. Programming Assignment #4
Binary Tree
A linked list but with two links per item
struct treeItem { type payload; treeItem *left, *right; };
left
right
payload
left
right
payload
left
right
payload
left
right
payload
left
right
payload
left
right
payload
left
right
payload
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Programming Assignment #4

13. Binary Tree (continued)
Binary tree needs a root
struct treeItem { type payload; treeItem *left, *right; };
struct treeItem *root;
Binary trees often drawn with root at top!
Unlike ordinary trees in the forest
More like the root systems of a tree
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Programming Assignment #4

14. Definitions (continued)
See K & R, §6.5
Binary Tree
A tree in which each element has two potential successors
Subtree
A node plus the set of all of its successors, either directly or indirectly
Root of a tree
The node of the tree that is not the successor to any other node, all other nodes are (directly or indirectly) successors to it
CS-2303, A-Term 2012
Programming Assignment #4

15. Programming Assignment #4
Binary Tree
A linked list but with two links per item
struct treeItem { type payload; treeItem *left, *right; };
left
right
payload
left
right
payload
left
right
payload
left
right
payload
left
right
payload
left
right
payload
left
right
payload
CS-2303, A-Term 2012
Programming Assignment #4

16. Programming Assignment #4
Purpose of a Tree
(Potentially) a very large data structure
Capable of storing very many items
In an orderly way
Need to find items by value
I.e., need to search through the data structure to see if it contains an item with the payload value we want
Need to add new items
If value is not already in the tree, add a new item …
…so that it can be easily found in future
Why not use a linked list?
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Programming Assignment #4

17. Searching and Adding to a Binary Tree
A linked list but with two links per item
struct treeItem { type payload; treeItem *left, *right; };
left
right
payload
Look recursively down sequence of branches until either
Desired node is found; or
Null branch is encountered
Replace with pointer to new item
Decide which branch to follow based on payload
left
right
payload
left
right
payload
left
right
payload
left
right
payload
left
right
payload
left
right
payload
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Programming Assignment #4

18. Example — Searching a Tree in C
typedef struct _treeItem { char *word; // part of payload int count; // part of payload _treeItem *left, *right; } treeItem; treeItem *findItem(treeItem *p, char *w) { if (p == NULL) return NULL; // item not found int c = strcmp(w, p->word); if (c == 0) return p; else if (c < 0) return findItem(p->left, w); else return findItem(p->right, w); }
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Programming Assignment #4

19. Notes on implementation in C++
class TreeNode { public: TreeNode(const string &w); ~TreeNode(); private: const string word; int count; TreeNode *left, *right; }; // class TreeNode
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Programming Assignment #4

20. Notes on implementation in C++ (continued)
class TreeNode { public: int incr(); int getCount(); string getWord(); int compare(const string &w2); TreeNode *setleft(TreeNode *t); TreeNode *setright(TreeNode *t); TreeNode *getleft(); TreeNode *getright();
TreeNode(const string &w);
~TreeNode();
private:
const string word; int count; TreeNode *left, *right;
}; // class TreeNode
TreeNode.h
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Programming Assignment #4

21. Notes on implementation in C++ (continued)
int TreeNode::incr() { return ++count; } // incr int TreeNode::getCount() { return count; } // getCount TreeNode *TreeNode::setLeft(TreeNode *newItem){ if (!left) return left = newItem; else { cerr << “Error message" << endl; return NULL; } } // setLeft
TreeNode::~TreeNode() { if (left) { delete left; left = NULL; } if (right) { delete right; right = NULL; } // TreeNode destructor TreeNode::TreeNode (const string &w){ // constructor deferred till // next time }
TreeNode.cpp
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Programming Assignment #4

22. Notes on implementation in C++ (continued)
class BinaryTree{ public: TreeNode *AddNode(const string &word); int getTotalNodes(); void PrintTree(ostream &output); BinaryTree(); //Default constructor ~BinaryTree(); //Destructor private: static int totalNodes; void PrintTree(TreeNode *subtree, ostream &output); TreeNode *AddNode(TreeNode *subtree, const string &word); TreeNode *root; }; // class BinaryTree
BinaryTree.h
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Programming Assignment #4

23. Programming Assignment #4
Additional Notes
See notes at the end of Programming Assignment document
Command line arguments (same as in C)
Input and Output streams
Absolute C++ Chapter 1 intro
Absolute C++ Chapter 12 in depth
Formatted output
CS-2303, A-Term 2012
Programming Assignment #4

24. Programming Assignment #4
Questions?
CS-2303, A-Term 2012
Programming Assignment #4