02 console class creation
DESCRIPTION
Class Creation DemoTRANSCRIPT
Lab C# Shape Class Console App
Brian Lai HKCT 2015 - 2016
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The Design: Top Down Approach
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1. We start with the Main program design on what to test. 2. Then, design class Shape on what methods in common. 3. Finally, design concrete classes: Circle and Rectangle, to support the class Shape.
The Idea: Shapes are extendable to classes such as Triangle, Oval, Text, Polygon
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The Main Program
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The Class Shape
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Class Circle
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Class Rectangle
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The Implementation: Bottom up Approach
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1. We test out the concrete classes: Circle and Rectangle. 2. Then, test the abstract class: Shape. 3. Main program is the test driver.
To Create a Class Right Click on the Project Title
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Then select Add, Class
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Change Class1.cs to your Class Name
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Rename Example: MyCircle.cs
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A Class MyCircle.cs file created
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Add Code to MyCircle Class
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Create MyRectangle Class
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Add Code to MyRectangle Class
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Having MyCircle and MyRectacgle classes defined.
Time to add code to the main
program.
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Add code to the Main Program
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The Main Program does not Work? Why?
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Answer: Cannot determine the circle object at compile time.
Run time allocation
Error !!!
The Fix: change run time to compile time allocation
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New the circle object at compile time.
Add rectangle object for testing
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Add Abstract class MyShape
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Add Code to MyShape: “virtual” is the key word
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Update class MyCircle: “override” is the key word
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Update class MyRectangle: override
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Main Program I: use of shapes array
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Up cast MyCircle And MyRectangle objects To shape.
Main Program II: output shapes array
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Sample Output
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How to add Triangle, Oval, Text, Polygon to the Design and the program
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Triangle
Polygon
End of Polymorphism Console App
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