Lesson 11: Mastering Mathematical Operations in VB2022

' Operations follow this order:
' 1. Parentheses ()
' 2. Exponentiation ^
' 3. Multiplication and Division *, /
' 4. Integer Division \
' 5. Modulus Mod
' 6. Addition and Subtraction +, -

Dim result = (5 + 3) * 2 ^ 3 ' = 8 * 8 = 64
Dim result2 = 5 + 3 * 2 ^ 3 ' = 5 + 3*8 = 5+24=29

' Common Math functions
Dim sqrt = Math.Sqrt(25) ' Square root: 5
Dim pow = Math.Pow(2, 3) ' Power: 8
Dim abs = Math.Abs(-10) ' Absolute value: 10
Dim round = Math.Round(3.14159, 2) ' Round to 2 decimals: 3.14
Dim max = Math.Max(5, 10) ' Maximum: 10
Dim min = Math.Min(5, 10) ' Minimum: 5
Dim pi = Math.PI ' Pi constant: 3.141592653589793

Private Sub BtnCalculateBMI_Click(sender As Object, e As EventArgs) Handles BtnCalculateBMI.Click
    Dim weight, height, bmi As Double
    
    ' Validate inputs
    If Not Double.TryParse(TxtWeight.Text, weight) Or weight <= 0 Then
        MessageBox.Show("Please enter a valid weight!")
        Return
    End If
    
    If Not Double.TryParse(TxtHeight.Text, height) Or height <= 0 Then
        MessageBox.Show("Please enter a valid height!")
        Return
    End If
    
    ' Calculate BMI: weight (kg) / [height (m)]^2
    bmi = weight / (height * height)
    
    ' Determine weight status
    Dim status As String
    Select Case bmi
        Case Is < 18.5
            status = "Underweight"
        Case 18.5 To 24.9
            status = "Normal weight"
        Case 25 To 29.9
            status = "Overweight"
        Case Else
            status = "Obese"
    End Select
    
    LblBMIResult.Text = $"BMI: {bmi.ToString("N1")} ({status})"
End Sub

Private Sub BtnCalculateVolume_Click(sender As Object, e As EventArgs) Handles BtnCalculateVolume.Click
    Dim volume As Double = 0
    
    Select Case cmbShape.SelectedItem.ToString()
        Case "Cube"
            Dim side = Double.Parse(TxtSide.Text)
            volume = Math.Pow(side, 3) ' side³
        Case "Cylinder"
            Dim radius = Double.Parse(TxtRadius.Text)
            Dim height = Double.Parse(TxtHeight.Text)
            volume = Math.PI * Math.Pow(radius, 2) * height
        Case "Sphere"
            Dim radius = Double.Parse(TxtRadius.Text)
            volume = (4 / 3) * Math.PI * Math.Pow(radius, 3)
        Case "Cone"
            Dim radius = Double.Parse(TxtRadius.Text)
            Dim height = Double.Parse(TxtHeight.Text)
            volume = (1 / 3) * Math.PI * Math.Pow(radius, 2) * height
    End Select
    
    LblVolumeResult.Text = "Volume: " & volume.ToString("N2")
End Sub