Docsity
Docsity
Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity

Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan

Guidelines and tips
Guidelines and tips
Sell on Docsity
Sell on Docsity
Docsity AI
Docsity AI
Log inSign up

Prepare for your exams

Study with the several resources on Docsity

Find documents

Prepare for your exams with the study notes shared by other students like you on Docsity

Search for your university

Find the specific documents for your university's exams

Docsity AINEW

Summarize your documents, ask them questions, convert them into quizzes and concept maps

Explore questions

Clear up your doubts by reading the answers to questions asked by your fellow students

Earn points to download

Earn points by helping other students or get them with a premium plan

Share documents
download point icon20 Points

For each uploaded document

Answer questions
download point icon5 Points

For each given answer (max 1 per day)

All the ways to get free points
Get points immediately

Choose a premium plan with all the points you need

Study Opportunities

Choose your next study program

Get in touch with the best universities in the world. Search through thousands of universities and official partners

Community

Ask the community

Ask the community for help and clear up your study doubts

Free resources

Our save-the-student-ebooks!

Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors

Defining Classes in Object-Oriented Programming: A C# Example with Time1 Class, Slides of C programming

Yale UniversityC programming

A lecture note from yale university's cs112 course on introduction to programming. It covers the topic of defining classes in object-oriented programming using c# as an example. The time1 class is used to represent time, and the document explains how to define instance variables, access modifiers, constructors, and methods for this class. The document also includes examples of using the class and testing its functionality.

Typology: Slides

2010/2011

Uploaded on 10/05/2011

christina
christina 🇺🇸

4.6

(23)

393 documents

1 / 5

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
1
CS 112 Introduction to
Programming
Lecture #16:
Defining Classes
http://flint.cs.yale.edu/cs112/
2
Outline
rAdmin. and review
rClasses and objects
rDefining classes
mBasic syntax
mExamples
3
PrintMonth GetMonthDays
GetMonthDays();
PrintMonth();
Main
Summary: Method Control Flow
4
Summary
rDesign
•Top-down; stepwise refinement
rImplementation and testing
•Write the simple functions first
•Write a piece and test a piece
–Test a method
»using some dummy method calls, e.g.
Call the method in Main() with some typical test cases
»using Visual Studio Immediate window
5
Outline
rAdmin. and review
ØClasses and objects
rDefining a class
mBasic syntax
mExamples
6
Object-Oriented Design
rThe focus of methods is on doing things;
roughly speaking, we can say that methods
focus on the verbs.
rIn object-oriented design, we focus on the
nouns
mIn object-oriented design, we tend to group
methods together according to the nouns
mImportant for large, complex programs
pf3
pf4
pf5

Partial preview of the text

Download Defining Classes in Object-Oriented Programming: A C# Example with Time1 Class and more Slides C programming in PDF only on Docsity!

CS 112 Introduction to

Programming

Lecture #16:

Defining Classes

http://flint.cs.yale.edu/cs112/

Outline

r Admin. and review

r Classes and objects

r Defining classes

m Basic syntax

m Examples

PrintMonth GetMonthDays

GetMonthDays();

PrintMonth();

Main

Summary: Method Control Flow

Summary

r Design

• Top-down; stepwise refinement

r Implementation and testing

• Write the simple functions first

• Write a piece and test a piece

– Test a method

» using some dummy method calls, e.g.

Call the method in Main() with some typical test cases

» using Visual Studio Immediate window

Outline

r Admin. and review

ÿ Classes and objects

r Defining a class

m Basic syntax

m Examples

Object-Oriented Design

r The focus of methods is on doing things;

roughly speaking, we can say that methods

focus on the verbs.

r In object-oriented design, we focus on the

nouns

m In object-oriented design, we tend to group

methods together according to the nouns

m Important for large, complex programs

C# Classes

r A C# class plays dual roles:

m Program module: containing a list of (static)

method declarations and (static) data fields

m Blueprint for generating objects

• It is the model or pattern from which objects are created

• Supports two techniques which are essence of object-

oriented programming

– “ data encapsulation ” (for abstraction)

– “ inheritance ” (for code reuse)

User-Defined Class

r A user-defined class is also called a user-defined

type

m class written by a programmer

r A class encapsulates (wrap together) data and

methods:

  • data members (member variables or instance variables)
  • methods that manipulate data members

Objects

r An object has:

m state - descriptive characteristics

m behaviors - what it can do (or be done to it)

r For example, consider a coin in a computer game

m The state of the coin is its current face (head or tail)

m The behavior of the coin is that it can be flipped

r Note the interactions between state and behaviors

m the behavior of an object might change its state

m the behavior of an object might depend on its state

Outline

r Admin. and review

r Classes and objects

ÿ Defining a class

ÿ Basic syntax

m Examples

public int x, y;

private char ch;

class MyClass

Defining Classes

r Use Project < Add Class to add a new class to your project

r A class contains data declarations and method

declarations

Data declarationsData declarations

Method declarationsMethod declarations

Member (data/method) Access Modifiers

public : member is accessible outside the class

private : member is accessible only inside the

class definition

Data Declarations

r You can define two types of variables in a class but not in any

method (called class variables )

m static class variables

m nonstatic variables are called instance variables (fields)

because each instance (object) of the class has its own copy

m class variables can be accessed in all methods of the class

r Comparison: Local variables

  • Variables declared within a method or within a block statement
  • Variables declared as local variables can only be accessed in

the method or the block where they are declared

Outline

TimeTest1.cs

Program Output

34 output += "\n\nAfter attempting invalid settings: " + 35 "\nUniversal time: " + time.ToUniversalString() + 36 "\nStandard time: " + time.ToStandardString(); 37 38 MessageBox.Show( output, "Testing Class Time1" ); 39 40 } // end method Main 41 42 } // end class TimeTest

Class View and Object Browser

r Class View and Object Browser are features

of Visual Studio that facilitate the design of

object-oriented applications

r Class View

m Displays variables and methods for all classes in a

project

m Displays as treeview hierarchical structure

m + at nodes allows nodes to be expanded

m - at nodes allows nodes to be collapsed

m Can be seen by selecting View < Class View

Class View: Example

Fig. 8.20 Class View of class Time1 and class TimeTest1.

Object Browser

r Object Browser

m Lists all classes in a library

m Helps developers learn about the functionality of a

specific class

m To view the Object Browser select any .NET FCL

method, right click, and select Go To Definition

Object Browser: Example

Object Browser when user selects MessageBox from TimesTest1.cs.

Example 2: The Coin Class

r We define a Coin class to model a coin in a game

r In our Coin class we could define the following data:

m face, an integer that represents the current face

m HEADS and TAILS, integer constants that represent the two

possible states

r We might also define the following methods:

m a Coin constructor, to set up the object

m a Flip method, to flip the coin

m a GetFace method, to return the current face

m a StateToString method, to return a string description of the

current state

r See Coin.cs, CountFlips.cs, FlipRace.cs

m To compile CountFlips: “csc CountFlips.cs Coin.cs”

m To compile FlipRace: “csc FlipRace.cs Coin.cs”

Instance Data: The Two Coins in FlipRace

int face;

class Coin

coin1: Coin

face = 0

coin2: Coin

face = 1

Backup Slides

Summary: Data Scope

r Variables declared in a larger scope can be

accessed in an enclosed scope, e.g.

m Variables declared in a class can be accessed by

the methods in the class

m Variables declared in a method can only be

accessed in the method

m Variables declared in a block can only be accessed

in the block