Manipulating Two .cs Files at a Time

1. Download the Rectangle project, extract it, and open it with VS. Note that in the “Solution Explorer”, there are two cs files listed: Program.cs and Rectangle.cs.
2. In the Solution Explorer, double-click on Rectangle.cs, and note how close it is from what was presented during the lecture.
3. In the Solution Explorer, double-click on Program.cs, and observe it.
4. Compile and execute the code.
5. Now, do the following:

• Introduce a syntactical error in Program.cs (e.g., remove a ;), and try to build the solution: what do you observe? Restore the program to its previous state, using CTRL + z to “undo” your operation.
• Introduce a syntactical error in Rectangle.cs (e.g., remove a ;), and try to build the solution: what do you observe? Undo the modification using CTRL + z.
• Add length = 12; in the main method of Program.cs and try to build the solution: what do you observe? Undo the modification using CTRL + z.

Enriching Program.cs

Edit the Main method of Program.cs by adding at its end statements that perform the following:

1. Create a second Rectangle object and set its length to 3 and its width to 3.
2. Create a third Rectangle object, and ask the user to specify its length and width. Display the area of this rectangle at the screen.
3. Create a fourth Rectangle object, do not specify its length or width, and display them at the screen. What do you observe?

In the last part, you may notice that the length and the width of the newly created object were assigned default values. To know more about this, refer to https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/default-values-table.

Editing Rectangle.cs

Edit Rectangle.cs:

1. Rename uniformly lengthParameter to lengthP in the SetLength method (that is, replace the two occurrences). You can use the symbol refactoring of C# to do so. Compile and run your program, what do you observe?
2. Some people use the convention of prefixing instance variables with _ (the underscore character), m (for “member”), or even m_. You will always find someone furiously advocating for one particular convention, the truth is that if you’re not forced to use one, you should pick whichever suits you best. Still, just to use it at least once, rename uniformly width into m_width and see how it feels. Compile and run your program, what do you observe? Either undo this modification, or rename length into m_length (you have to be consistent!).
3. Change the name of one of the accessor method in Rectangle.cs without changing it in Program.cs. Compile and run your program, what do you observe? Undo your modification.

Enriching Rectangle.cs

By taking inspiration from the ComputeArea() method, write three new methods:

1. A method that returns the perimeter of the calling object.
2. A method that double the length and the width of the calling object.
3. A method that swap the length and the width of the calling object.

For each method, pick a (valid) name, think about the return type and the parameters, and write the body of the method carefully. After compliation succeed, call that method in Program.cs and see if it has the expected behaviour.