Visual Basic BMI Calculator gives NaN result - vb.net

Question

I'm doing an IT course for college and one of the assignments requires you to create a BMI calculator in Visual Basic with the use of object orientated techniques. I'm not a very good programmer and thus I'm stuck on a problem I keep receiving. The code I'm using was given to me by someone who claimed it works, however when I run the program any results given are NaN.
Anyone have an idea as to what is wrong with the code in order to give me this result?
Here is the code I'm using:
Public Class Form1
Private Sub Button_Calculate_Click(sender As Object, e As EventArgs) Handles
Button_Calculate.Click
Dim height As Double = Double.Parse(TextBox_Height.Text)
Dim weight As Double = Double.Parse(TextBox_Weight.Text)
bmi.SetWeight(weight)
bmi.SetHeight(height)
TextBox_BMI.Text = Format(bmi.GetBMI(), "0.00")
End Sub
Private bmi As New BMI
End Class
In a separate class:
Public Class BMI
Public Function GetBMI()
Return (weight / (height ^ 2))
End Function
Public Function GetWeight()
Return weight
End Function
Public Function GetHeight()
Return height
End Function
Public Function SetWeight(_weight As Double)
Return weight = _weight
End Function
Public Function SetHeight(_height As Double)
Return height = _height
End Function
Private weight As Double
Private height As Double
End Class

Answer 1

There are a few problems with your (meaning kushlord420) solution.
Visual Basic code in case insensitive so bmi is the same as BMI
You never use the Form level variable bmi so delete.
You tried to write a custom constructor but in vb.net it is Sub New
You are converting the values in the weight and height text boxes to Double but your properties are type Single. Actually this should
be Single.TryParse but that is for another day.
Functions in vb.net must have a data type for the return value. This is provided in the first line of the function. Since you are
using Format on the return value I made the value a String and
converted the return value.
Fixed the constructor parameters to avoid ambiguity.
Sub Button_Calculate_Click(sender As Object, e As EventArgs) Handles Button_Calculate.Click
Dim bmi As New BMI(CSng(TextBox_Weight.Text), CSng(TextBox_Height.Text))
TextBox_BMI.Text = Format(bmi.GetBMI(), "0.00")
End Sub
Public Class BMI
Public Function GetBMI() As String
Return (Weight / (Height ^ 2)).ToString
End Function
Public Property Weight As Single
Public Property Height As Single
Public Sub New(wght As Single, hght As Single)
Weight = wght
Height = hght
End Sub
End Class

Answer 2

You really need something more like this:
Public Class BMI
Public Function GetBMI() As Double
Return (weight / (height ^ 2))
End Function
Public Property Weight As Double
Public Property Height As Double
Public Sub New(weight As Double, height As Double)
Me.Weight = weight
Me.Height = height
End Sub
End Class
Public Class Form1
Private Sub Button_Calculate_Click(sender As Object, e As EventArgs) Handles Button_Calculate.Click
Dim bmi As New BMI(CDbl(TextBox_Weight.Text), CDbl(TextBox_Height.Text))
TextBox_BMI.Text = Format(bmi.GetBMI(), "0.00")
End Sub
End Class
Or better yet, this:
Public Class BMI
Public Property Weight As Double
Public Property Height As Double
Public ReadOnly Property BMI As Double
Get
Return (Weight / (Height ^ 2))
End Get
End Property
Public Sub New()
End Sub
Public Sub New(weight As Double, height As Double)
Me.Weight = weight
Me.Height = height
End Sub
End Class

Answer 3

With the help of a friend, figured out my problem.
If anyone is curious, here is the code that made it work:
Public Class Form1
Sub Button_Calculate_Click(sender As Object, e As EventArgs) Handles
Button_Calculate.Click
Dim bmi As New BMI With {.Weight = CDbl(TextBox_Weight.Text), .Height =
CDbl(TextBox_Height.Text)}
TextBox_BMI.Text = Format(bmi.GetBMI(), "0.00")
End Sub
Private bmi As New BMI
End Class
And:
Public Class BMI
Public Function GetBMI()
Return (weight / (height ^ 2))
End Function
Property Weight As Single
Property Height As Single
Public Sub BMI(weight As Single, height As Single)
Me.Weight = weight
Me.Height = height
End Sub
End Class