Lesson 11: Mathematical Operations in VB2019

Private Sub BtnCalculate_Click(sender As Object, e As EventArgs) Handles BtnCalculate.Click
    ' Get input values
    Dim num1 As Single = CSng(TxtNum1.Text)
    Dim num2 As Single = CSng(TxtNum2.Text)
    
    ' Perform calculations
    Dim sum As Single = num1 + num2
    Dim diff As Single = num1 - num2
    Dim prod As Single = num1 * num2
    Dim quot As Single = num1 / num2
    
    ' Display results
    LblSum.Text = CStr(sum)
    LblDiff.Text = CStr(diff)
    LblProduct.Text = CStr(prod)
    LblQuotient.Text = CStr(quot)
End Sub

Private Sub BtnCalculateHyp_Click(sender As Object, e As EventArgs) Handles BtnCalculateHyp.Click
    ' Get side lengths
    Dim sideA As Double = CDbl(TxtSideA.Text)
    Dim sideB As Double = CDbl(TxtSideB.Text)
    
    ' Calculate hypotenuse using Pythagoras Theorem
    Dim hypotenuse As Double = Math.Sqrt(sideA ^ 2 + sideB ^ 2)
    
    ' Display result
    LblHypotenuse.Text = "c = " & Math.Round(hypotenuse, 2).ToString()
    
    ' Draw a visual representation of the triangle
    Dim myPen As New Pen(Color.Blue, 3)
    Dim ptA As New Point(50, 50)
    Dim ptB As New Point(50 + sideA * 10, 50)
    Dim ptC As New Point(50, 50 + sideB * 10)
    Dim points() As Point = {ptA, ptB, ptC}
    
    Dim g As Graphics = Me.CreateGraphics()
    g.Clear(Color.White)
    g.DrawPolygon(myPen, points)
End Sub

Private Sub BtnCalculateBMI_Click(sender As Object, e As EventArgs) Handles BtnCalculateBMI.Click
    ' Get user input
    Dim height As Double = CDbl(TxtHeight.Text)
    Dim weight As Double = CDbl(TxtWeight.Text)
    
    ' Calculate BMI
    Dim bmi As Double = weight / (height ^ 2)
    
    ' 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 Is >= 30
            status = "Obesity"
    End Select
    
    ' Display results
    LblBMI.Text = "BMI: " & Math.Round(bmi, 2).ToString()
    LblStatus.Text = "Status: " & status
End Sub

Private Sub BtnCalculateInterest_Click(sender As Object, e As EventArgs) Handles BtnCalculateInterest.Click
    ' Get input values
    Dim principal As Double = CDbl(TxtPrincipal.Text)
    Dim rate As Double = CDbl(TxtRate.Text) / 100  ' Convert percentage to decimal
    Dim years As Integer = CInt(TxtYears.Text)
    Dim compoundsPerYear As Integer = CInt(TxtCompounds.Text)
    
    ' Calculate compound interest
    Dim amount As Double = principal * (1 + rate / compoundsPerYear) ^ (compoundsPerYear * years)
    
    ' Display result
    LblFutureValue.Text = "Future Value: $" & Math.Round(amount, 2).ToString()
End Sub