Programming Abstraction in C++ Eric S. Roberts and Julie Zelenski - - PowerPoint PPT Presentation

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Programming Abstraction in C++ Eric S. Roberts and Julie Zelenski - - PowerPoint PPT Presentation

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators Programming Abstraction in C++ Eric S. Roberts and Julie Zelenski Stanford University 2010 Vector Class Grid Class Stack Class Queue Class

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Programming Abstraction in C++

Eric S. Roberts and Julie Zelenski

Stanford University 2010

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Chapter 4. Using Abstract Data Types

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Outline

1

Vector Class

2

Grid Class

3

Stack Class

4

Queue Class

5

Map Class

6

Lexicon Class

7

Scanner Class

8

Iterators

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Introduction

Abstract data type (ADT): A type defined in terms of its

  • behavior. (Rather than its representation, e.g., char is

represented by codes.)

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Introduction

Abstract data type (ADT): A type defined in terms of its

  • behavior. (Rather than its representation, e.g., char is

represented by codes.) Separating behavior from implementation

  • Simplicity. Hiding internal representation from the client.
  • Flexibility. Implementation can be changed as long as the

interface (behavior) remains the same.

  • Security. Protect the implementation from the client.
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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Introduction

Abstract data type (ADT): A type defined in terms of its

  • behavior. (Rather than its representation, e.g., char is

represented by codes.) Separating behavior from implementation

  • Simplicity. Hiding internal representation from the client.
  • Flexibility. Implementation can be changed as long as the

interface (behavior) remains the same.

  • Security. Protect the implementation from the client.

Seven classes: Vector, Grid, Stack, Queue, Map, Lexicon, Scanner.

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Outline

1

Vector Class

2

Grid Class

3

Stack Class

4

Queue Class

5

Map Class

6

Lexicon Class

7

Scanner Class

8

Iterators

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Vector class

A container class or collection class. Interface #include "vector.h" A naming convention. For example: grid.h, stack.h. Generalization of one-dimensional array type Variable size Effective size available Simple insert and delete Bound checking

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Vector class (cont.)

Constructor Vector<int> vec; Specify the base type of a vector.

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Vector class (cont.)

Constructor Vector<int> vec; Specify the base type of a vector.

  • Methods. Table 4-1, p. 127.

Example. vec.add(10), vec.removeAt(0).

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Vector class (cont.)

Constructor Vector<int> vec; Specify the base type of a vector.

  • Methods. Table 4-1, p. 127.

Example. vec.add(10), vec.removeAt(0).

  • Question. How would you remove the last entry?
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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Idiom

Idiom: Going through a vector, p. 129

void PrintVector(Vector<int> & vec) { cout << "["; for (int i = 0; i < vec.size(); i++) { if (i > 0) cout << ", "; cout << vec[i]; } cout << "]" << endl; }

  • Note. Passing by reference.
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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Idiom

Idiom: Going through a vector, p. 129

void PrintVector(Vector<int> & vec) { cout << "["; for (int i = 0; i < vec.size(); i++) { if (i > 0) cout << ", "; cout << vec[i]; } cout << "]" << endl; }

  • Note. Passing by reference.

Question: Can you pass vec by value (without the ampersand)? If you can, what are the differences?

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Passing by reference

void AddArrayToVector(Vector<int> & vec, int array[], int n) { for (int 1 = 0; i < n; i++) { vec.add(array[i]); } }

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Passing by reference

void AddArrayToVector(Vector<int> & vec, int array[], int n) { for (int 1 = 0; i < n; i++) { vec.add(array[i]); } }

Question: Can you pass vec by value (without the ampersand)? If you can, what are the differences?

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Passing by reference

void AddArrayToVector(Vector<int> & vec, int array[], int n) { for (int 1 = 0; i < n; i++) { vec.add(array[i]); } }

Question: Can you pass vec by value (without the ampersand)? If you can, what are the differences? Almost always pass classes by reference.

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Idiom

Idiom: Open a text file, p. 131

void AskUserForInputFile(string promt, ifstream & infile) { while (true) { cout << prompt; string filename = GetLine(); infile.open(filename.c_str()); if (!infile.fail()) break; cout << "Unable to open " << filename << endl; infile.clear(); } }

  • Note. Don’t forget infile.close() after reading/writing.
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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Idiom

Idiom: Open a text file, p. 131

void AskUserForInputFile(string promt, ifstream & infile) { while (true) { cout << prompt; string filename = GetLine(); infile.open(filename.c_str()); if (!infile.fail()) break; cout << "Unable to open " << filename << endl; infile.clear(); } }

  • Note. Don’t forget infile.close() after reading/writing.

Study revfile.cpp, p. 130. A text file as lines, an object of Vector<string>.

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Outline

1

Vector Class

2

Grid Class

3

Stack Class

4

Queue Class

5

Map Class

6

Lexicon Class

7

Scanner Class

8

Iterators

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Grid class

Generalization of two-dimensional array. Variable dimensions. Constructor Grid<double> matrix(3,2); Specify row and column dimensions, in addition to the base type.

  • Methods. Table 4-2, p. 132
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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Example

CheckForWin for the tic-tac-toe game, p. 133.

bool CheckForWin(Grid<char> & board, char mark) { for (int i = 0; i <3; i++) { if (CheckLine(board, mark, i, 0, 0, 1)) return true; if (CheckLine(board, mark, 0, i, 1, 0)) return true; } if (CheckLine(board, mark, 0, 0, 1, 1)) return true; return (CheckLine(board, mark, 2, 0, -1, 1)); }

check rows check columns check diagonal check antidiagonal

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Outline

1

Vector Class

2

Grid Class

3

Stack Class

4

Queue Class

5

Map Class

6

Lexicon Class

7

Scanner Class

8

Iterators

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Stack class

Behavior: Last in, first out (LIFO). Only the top is accessible to the client. Fundamental operations: push, pop

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Stack class

Behavior: Last in, first out (LIFO). Only the top is accessible to the client. Fundamental operations: push, pop

  • Applications. Nested function calls:

main() { call function F } function F() { call function G }

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Stack class (cont.)

Function G is called last and returns first.

main local variables for F local variables for G

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Stack class (cont.)

Constructor Stack<double> calculator; Specify a base type.

  • Methods. Table 4-3, p. 135.
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Stack class (cont.)

Constructor Stack<double> calculator; Specify a base type.

  • Methods. Table 4-3, p. 135.
  • Example. Scientific calculator (HP C-13)

50.0 * 1.5 + 3.8 / 2.0 Reverse Polish notation (RPN): 50.0 ENTER 1.5 * 3.8 ENTER 2.0 / +

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RPN and stack

When the ENTER button is pressed, the previous value is pushed on a stack. When an operator button is pressed Pushing the previous value Popping two values Applying the operation to the two values Pushing the result on the stack

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Example

50.0 ENTER 1.5 * 3.8 ENTER 2.0 / + Stack content, p. 136.

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Example

50.0 ENTER 1.5 * 3.8 ENTER 2.0 / + Stack content, p. 136.

  • Question. What is the key sequence for

50.0 * (1.5 + 3.8) / 2.0 Think the stack content.

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Example

50.0 ENTER 1.5 * 3.8 ENTER 2.0 / + Stack content, p. 136.

  • Question. What is the key sequence for

50.0 * (1.5 + 3.8) / 2.0 Think the stack content. An RPN calculator simulator, pp. 137–138.

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Outline

1

Vector Class

2

Grid Class

3

Stack Class

4

Queue Class

5

Map Class

6

Lexicon Class

7

Scanner Class

8

Iterators

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Queue class

  • Behavior. First in, first out (FIFO). Only the head and tail are

accessible to the client. Fundamental operations: enqueue, dequeue Constructor Queue<int> queue;

  • Methods. Table 4-4, p. 139.
  • Application. Printer queue.
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Example

Check-out line simulation. Models Discretize time to serialize events. Arrival process: Poisson distribution. Average probability of a customer arriving in a particular time interval. Parameter: ARRIVAL PROBABILITY Implementation: RandomChance(ARRIVAL PROBABILITY) Service time: Uniformly distributed within a range. Parameters: MIN SERVICE TIME, MAX SERVICE TIME Implementation: RandomInteger(MIN SERVICE TIME, MAX SERVICE TIME)

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Check-out line simulation (cont.)

Simulating time. Parameter: SIMULATION TIME Implementation:

for (int t = 0; t < SIMULATION_TIME; t++) { if (RandomChance(ARRIVAL_PROBABILITY)) { queue.enqueue(t); } if (serviceTimeRemaining > 0) { serviceTimeRemaining--; if (serviceTimeRemaining == 0) nServed++; } else { totalWait = t - queue.dequeue(); serviceTimeRemaining = RandomInteger(MIN_..., MAX_...); } totalLength += queue.size(); }

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Outline

1

Vector Class

2

Grid Class

3

Stack Class

4

Queue Class

5

Map Class

6

Lexicon Class

7

Scanner Class

8

Iterators

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Map class

  • Behavior. An association between a key (tag) and an

associated value (can be a complicated structure). A generalization of Vector. Fundamental operations: put, get

  • Application. Symbol table, an association between a variable

name and its value.

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Map class

  • Behavior. An association between a key (tag) and an

associated value (can be a complicated structure). A generalization of Vector. Fundamental operations: put, get

  • Application. Symbol table, an association between a variable

name and its value. Constructor Map<double> symbolTable;

  • Note. The base type is the type of value, not tag.

For simplicity, the type of tag is always string.

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Map class

  • Behavior. An association between a key (tag) and an

associated value (can be a complicated structure). A generalization of Vector. Fundamental operations: put, get

  • Application. Symbol table, an association between a variable

name and its value. Constructor Map<double> symbolTable;

  • Note. The base type is the type of value, not tag.

For simplicity, the type of tag is always string.

  • Methods. Table 4-5, p.147.
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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Map class

  • Behavior. An association between a key (tag) and an

associated value (can be a complicated structure). A generalization of Vector. Fundamental operations: put, get

  • Application. Symbol table, an association between a variable

name and its value. Constructor Map<double> symbolTable;

  • Note. The base type is the type of value, not tag.

For simplicity, the type of tag is always string.

  • Methods. Table 4-5, p.147.
  • Example. Airport codes. Figure 4-6, p. 150.
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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Outline

1

Vector Class

2

Grid Class

3

Stack Class

4

Queue Class

5

Map Class

6

Lexicon Class

7

Scanner Class

8

Iterators

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Lexicon class

  • Behavior. A list of alphabetically ordered words.

Fundamental operations: add, containsWord

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Lexicon class

  • Behavior. A list of alphabetically ordered words.

Fundamental operations: add, containsWord Constructors Lexicon wordList; Lexicon english("EnglishWords.dat");

  • Note. No parameterized type (always string)

Formats of the data file text file, list of words, one word per line precompiled data file

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Lexicon class (cont.)

  • Methods. Table 4-6, p. 152.
  • Example. twoletters.cpp, p. 153.

Check every possible two-letter combinations (262), if it is contained in EnglishWords.dat.

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Lexicon class (cont.)

  • Methods. Table 4-6, p. 152.
  • Example. twoletters.cpp, p. 153.

Check every possible two-letter combinations (262), if it is contained in EnglishWords.dat. Why Lexicon now that we have Map?

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Lexicon class (cont.)

  • Methods. Table 4-6, p. 152.
  • Example. twoletters.cpp, p. 153.

Check every possible two-letter combinations (262), if it is contained in EnglishWords.dat. Why Lexicon now that we have Map? Efficiency.

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Outline

1

Vector Class

2

Grid Class

3

Stack Class

4

Queue Class

5

Map Class

6

Lexicon Class

7

Scanner Class

8

Iterators

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Scanner class

  • Behavior. Divide up a string into tokens

A sequence of consecutive alphanumeric characters, or A single-character string consisting of a space or punctuation mark. Fundamental operation: hasMoreTokens, nextToken Constructor Scanner scanner; No base type. (Always string.)

  • Methods. Table 4-7, p. 157.
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Idiom

Idiom: Scan a file ifstream infile; Scanner scanner; AskUserForInputFile("Input file: ", infile); scanner.setInput(infile); while (scanner.hasMoreTokens()) { string word = scanner.nextToken(); ... do something with the token ... } infile.close();

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Outline

1

Vector Class

2

Grid Class

3

Stack Class

4

Queue Class

5

Map Class

6

Lexicon Class

7

Scanner Class

8

Iterators

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Iterators

Iterator: A subclass (of Vector, Grid, Map, Lexicon, Scanner).

  • Behavior. Stepping through the elements of a collection class.

Fundamental operations: hasNext, next

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

Iterators (cont.)

Idiom: iterator, p. 158 Lexicon::Iterator iter = english.iterator(); while (iter.hasNext()) { string word = iter.next(); ... code to work with the word ... } Lexicon::Iterator A subclass of Lexicon iter An object of the class Lexicon::Iterator iter.next() Returns a value of type string (Lexicon) or base type (Vector or Grid or Map).

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foreach mechanism

Usage Idiom: foreach foreach (string word in english) { if (word.length() == 2) { cout << word << endl; } }

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Vector Class Grid Class Stack Class Queue Class Map Class Lexicon Class Scanner Class Iterators

foreach mechanism

Usage Idiom: foreach foreach (string word in english) { if (word.length() == 2) { cout << word << endl; } } It is simple and easy to use, but you should understand the

  • mechanism. The type of word (string) must match the base

type of the class (Lexicon) of which english is an object.