Wolves and Sheep Exercise
In this studio, you will concentrate on data validation using if clauses.
You will complete a program that requires the user to solve a puzzle.
In this puzzle, you need to help three sheep and three wolves cross a river.
They can use a raft that holds a minimum of one and a maximum of two animals
at a time. Beware: If the wolves outnumber the sheep on either bank, the
sheep will be eaten up.
You are given a partial program for this puzzle. You can download the
program code from here.
After you download the application, make sure you extract the files first
and then click on the solution object to open the application. You will
probably have to allow it to convert the files as well--Visual Studio will
tell you if it needs to do this. Once it's open, run the program to see how
it works. It allows you move sheep and wolves from one side to another. It
disables the move button on the other side of the bank to make sure the raft
can only move in one direction.
The given program does not have any error checking. In this studio, you will
add the error checking to the "Move To Right" button only. You need not make
any other changes to the program.
If you have time, you can copy the code you generate to the "Move to Left"
button and adapt it to the left side to complete the program. You can find
the completed executable program here, if you want to check against it.
First add code to check that the input data contains numbers. If there is a
problem, display an error message in the label (lblMessage). Cut and paste
your if statement(s) below.
Student Response: If Not IsNumeric(Me.txtWolfToMove.Text) Or Not
IsNumeric(Me.txtSheepToMove.Text) Then
MsgBox("Enter a valid number of wolf and sheep to transfer")
Me.txtWolfToMove.Text = Nothing
Me.txtSheepToMove.Text = Nothing
Exit Sub
Score: 10/10
3.
Now, add code to check that we are moving 1 or 2 animals. If there is a
problem, display an error message in the label (lblMessage). Cut and paste
your if statement(s) below.
Student Response: Dim condAnimalMovingLimit As Boolean
condAnimalMovingLimit = (Val(txtWolfToMove.Text) + Val(txtSheepToMove.Text)
<= 2) AndAlso (Val(txtWolfToMove.Text) + Val(txtSheepToMove.Text) >= 0)
ElseIf Not condAnimalMovingLimit Then
lblMessage.Text = "Enter a valid number of wolf and sheep to transfer"
Me.txtWolfToMove.Text = Nothing
Me.txtSheepToMove.Text = Nothing
Exit Sub
Score: 8/10
Comments: awkward code, wouldn't run or compile. You need an if
statement with your ElseIf.
4.
Now, add code to check that we are not moving more animals than are left on
the bank of the river. For example, if I want to move two animals, there
must be at least two animals on that side of the river bank. If there is a
problem, display an error message in the label (lblMessage). Cut and paste
your if statement(s) below.
Student Response: Dim EnoughAnimalLimit As Boolean
EnoughAnimalLimit = (Val(txtSheepToMove.Text) <=
Val(lblLeftSheepCount.Text)) Or (Val(txtWolfToMove.Text) <=
Val(lblLeftWolfCount.Text))
-----------------
ElseIf Not condAnimalMovingLimit Or Not EnoughAnimalLimit Then
lblMessage.Text = "Enter a valid number of wolf and sheep to transfer"
Me.txtWolfToMove.Text = Nothing
Me.txtSheepToMove.Text = Nothing
Exit Sub
Score: 10/10
5.
Now, add code to check whether sheep outnumber the wolves on either bank
after the move. If so, disable both the move buttons (using the buttons'
Enabled property) and notify the user that they lost the game. Cut and paste
your if statement(s) below.
Student Response: 'Player loses checker
If ((Val(lblLeftWolfCount.Text) > Val(lblLeftSheepCount.Text)) And
Val(lblLeftSheepCount.Text) > 0) Or ((Val(lblRightWolfCount.Text) >
Val(lblRightSheepCount.Text)) And Val(lblRightSheepCount.Text > 0)) Then
lblMessage.Text = "You have lost!"
Me.btnMoveToRight.Enabled = False
Me.btnMoveToLeft.Enabled = False
End If
Score: 10/10
6.
Show your code to the TA and get their approval code. If you have finished
the program, see if you can you solve the puzzle.
Student Response Value
1. sean henley 0%
Score: 0/10
New score: 10/10 This score has been adjusted by the grader.