Public Class Form1
    ' Declare variables for arithmetic operations
    Dim first_number As Double
    Dim second_number As Double
    Dim a As Double
    Dim Arithop As String
    Dim n As Int64

    ' Event handler for numeric buttons (0-9, dot)
    Private Sub Button_Click(sender As Object, e As EventArgs) Handles btn9.Click, btn8.Click, btn7.Click, btndot.Click, btn6.Click, btn5.Click, btn4.Click, btn3.Click, btn2.Click, btn1.Click, btn0.Click
        ' Cast the sender as a Button
        Dim b As Button = sender

        ' Update the display when a numeric button is clicked
        If Label1.Text = "0" Then
            Label1.Text = b.Text
        Else
            Label1.Text = Label1.Text + b.Text
        End If
    End Sub

    ' Event handler for the clear button
    Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click
        ' Get the text from Label1 and Label2
        Dim label1Text As String = Label1.Text
        Dim label2Text As String = Label2.Text

        ' Remove the last character from Label1
        If label1Text.Length > 1 Then
            Label1.Text = label1Text.Substring(0, label1Text.Length - 1)
        Else
            Label1.Text = "0"
        End If

        ' Remove the last character from Label2
        If label2Text.Length > 1 Then
            Label2.Text = label2Text.Substring(0, label2Text.Length - 1)
        Else
            Label2.Text = ""
        End If
    End Sub

    ' Event handler for the clear entry button
    Private Sub btnClearEntry_Click(sender As Object, e As EventArgs) Handles btnClearEntry.Click
        ' Clear both labels
        Label1.Text = "0"
        Label2.Text = ""
    End Sub

    ' Event handler for arithmetic operation buttons (+, -, *, /, Mod, Exp)
    Private Sub Arithmetic_fuctions(sender As Object, e As EventArgs) Handles btnMult.Click, btnMod.Click, btnMinus.Click, BtnExp.Click, btndiv.Click, btnAdd.Click
        ' Cast the sender as a Button
        Dim ops As Button = sender

        ' Store the current number from Label1 and the selected operation
        first_number = Label1.Text
        Label2.Text = Label1.Text
        Label1.Text = ""
        Arithop = ops.Text
        Label2.Text = Label2.Text + " " + Arithop
    End Sub

    ' Event handler for the equals button (=)
    Private Sub btnequals_Click(sender As Object, e As EventArgs) Handles btnequals.Click
        ' Retrieve the second number from Label1 and perform the selected operation
        second_number = Label1.Text
        If Arithop = "+" Then
            a = first_number + second_number
            Label1.Text = a
            Label2.Text = ""
        ElseIf Arithop = "-" Then
            a = first_number - second_number
            Label1.Text = a
            Label2.Text = ""
        ElseIf Arithop = "*" Then
            a = first_number * second_number
            Label1.Text = a
            Label2.Text = ""
        ElseIf Arithop = "/" Then
            a = first_number / second_number
            Label1.Text = a
            Label2.Text = ""
        ElseIf Arithop = "Mod" Then
            a = first_number Mod second_number
            Label1.Text = a
            Label2.Text = ""
        ElseIf Arithop = "Exp" Then
            a = first_number ^ second_number
            Label1.Text = a
            Label2.Text = ""
        End If
    End Sub

    ' Event handler for the binary conversion button
    Private Sub btnBin_Click(sender As Object, e As EventArgs) Handles btnBin.Click
        If Int64.TryParse(Label1.Text, n) Then
            ' Convert the number to binary and update Label1
            Label1.Text = Convert.ToString(n, 2)
        Else
            Label1.Text = ""
        End If
    End Sub

    ' Event handlers for various trigonometric functions
    Private Sub btnSin_Click(sender As Object, e As EventArgs) Handles btnSin.Click
        a = Math.Sin(Label1.Text)
        Label1.Text = a
        Label2.Text = ""
    End Sub

    Private Sub btnCos_Click(sender As Object, e As EventArgs) Handles btnCos.Click
        a = Math.Cos(Label1.Text)
        Label1.Text = a
        Label2.Text = ""
    End Sub

    Private Sub btnTan_Click(sender As Object, e As EventArgs) Handles btnTan.Click
        a = Math.Tan(Label1.Text)
        Label1.Text = a
        Label2.Text = ""
    End Sub

    Private Sub btnCosh_Click(sender As Object, e As EventArgs) Handles btnCosh.Click
        a = Math.Cosh(Label1.Text)
        Label1.Text = a
        Label2.Text = ""
    End Sub

    Private Sub btnSinh_Click(sender As Object, e As EventArgs) Handles btnSinh.Click
        a = Math.Sinh(Label1.Text)
        Label1.Text = a
        Label2.Text = ""
    End Sub

    Private Sub btnTanh_Click(sender As Object, e As EventArgs) Handles btnTanh.Click
        a = Math.Tanh(Label1.Text)
        Label1.Text = a
        Label2.Text = ""
    End Sub

    ' Event handler for logarithm base 10
    Private Sub btnLog_Click(sender As Object, e As EventArgs) Handles btnLog.Click
        a = Math.Log10(Label1.Text)
        Label1.Text = a
        Label2.Text = ""
    End Sub

    ' Event handler for changing the sign of the number
    Private Sub btnPlusMinus_Click(sender As Object, e As EventArgs) Handles btnPlusMinus.Click
        Dim q As Double
        q = Convert.ToDouble(Label1.Text)
        Label1.Text = Convert.ToString(-1 * q)
    End Sub

    ' Event handler for clearing and resetting the calculator
    Private Sub btnBackSpace_Click(sender As Object, e As EventArgs) Handles btnBackSpace.Click
        Label1.Text = "0"
        first_number = 0
        second_number = 0
    End Sub

    ' Event handler for calculating cube roots
    Private Sub btnCubeRoot_Click(sender As Object, e As EventArgs) Handles btnCubeRoot.Click
        Dim inputvalue As Double
        If Double.TryParse(Label1.Text, inputvalue) Then
            a = Math.Pow(inputvalue, 1.0 / 3.0)
            Label1.Text = a.ToString()
            Label2.Text = ""
        Else
            Label1.Text = "Invalid input"
            Label2.Text = ""
        End If
    End Sub

    ' Event handler for square roots
    Private Sub btnsqrt_Click(sender As Object, e As EventArgs) Handles btnsqrt.Click
        a = Math.Sqrt(Label1.Text)
        Label1.Text = a
        Label2.Text = ""
    End Sub

    ' Event handler for inserting the value of pi
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles btnPi.Click
        Label1.Text = "3.141592653589976323"
    End Sub

    ' Event handler for natural logarithm
    Private Sub btnNaturalLog_Click(sender As Object, e As EventArgs) Handles btnNaturalLog.Click
        a = Math.Log(Label1.Text)
        Label1.Text = a
        Label2.Text = ""
    End Sub

    ' Event handler for calculating the cube of a number
    Private Sub btnCube_Click(sender As Object, e As EventArgs) Handles btnCube.Click
        Dim inputValue As Double
        If Double.TryParse(Label1.Text, inputValue) Then
            Dim cube As Double = inputValue * inputValue * inputValue
            Label1.Text = cube.ToString()
            Label2.Text = ""
        Else
            Label1.Text = "Invalid input"
            Label2.Text = ""
        End If
    End Sub

    ' Event handler for calculating the square of a number
    Private Sub btnsquare_Click(sender As Object, e As EventArgs) Handles btnsquare.Click
        Dim inputValue As Double
        If Double.TryParse(Label1.Text, inputValue) Then
            Dim square As Double = inputValue * inputValue
            Label1.Text = square.ToString()
            Label2.Text = ""
        Else
            Label1.Text = "Invalid input"
            Label2.Text = ""
        End If
    End Sub

    ' Event handler for converting to octal
    Private Sub btnOct_Click(sender As Object, e As EventArgs) Handles btnOct.Click
        If Int64.TryParse(Label1.Text, n) Then
            Label1.Text = Convert.ToString(n, 8)
        Else
            Label1.Text = ""
        End If
    End Sub

    ' Event handler for converting to hexadecimal
    Private Sub btnHex_Click(sender As Object, e As EventArgs) Handles btnHex.Click
        If Int64.TryParse(Label1.Text, n) Then
            Label1.Text = Convert.ToString(n, 16)
        Else
            Label1.Text = ""
        End If
    End Sub

    ' Event handler for calculating the reciprocal
    Private Sub btnReciprocal_Click(sender As Object, e As EventArgs) Handles btnReciprocal.Click
        Dim inputValue As Double
        If Double.TryParse(Label1.Text, inputValue) Then
            If inputValue = 0 Then
                Label1.Text = "Cannot divide by zero"
                Label2.Text = ""
            Else
                Dim reciprocal As Double = 1.0 / inputValue
                Label1.Text = reciprocal.ToString()
                Label2.Text = ""
            End If
        Else
            Label1.Text = "Invalid input"
            Label2.Text = ""
        End If
    End Sub

    ' Event handler for initializing the unit conversion ComboBox
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        ' Set the initial text for ComboBox
        ComboBox1.Text = "Choose one ...."

        ' Add items to the ComboBox for unit conversions
        ComboBox1.Items.Add("Celcious to Fahrenheit")
        ComboBox1.Items.Add("Fahrenheit to Celcious")
        ComboBox1.Items.Add("Miles to Kilometers")
        ComboBox1.Items.Add("Kilometers to Miles")
        ComboBox1.Items.Add("Centimeter to Meter")
        ComboBox1.Items.Add("Meter to Centimeter")
        ComboBox1.Items.Add("Celcious to Kelvin")
        ComboBox1.Items.Add("Kelcin to Celcious")
    End Sub

    ' Event handler for performing unit conversions
    Private Sub btnConvert_Click(sender As Object, e As EventArgs) Handles btnConvert.Click
        Dim convt As Double
        If ComboBox1.Text = "Celcious to Fahrenheit" Then
            ' Perform Celsius to Fahrenheit conversion
            convt = (9 / 5 * Double.Parse(TextBox1.Text)) + 32
            Label4.Text = convt & " Fahrenheit"
        ElseIf ComboBox1.Text = "Fahrenheit to Celcious" Then
            ' Perform Fahrenheit to Celsius conversion
            convt = (5 / 9 * (Double.Parse(TextBox1.Text) - 32))
            Label4.Text = convt & " Celcious"
        ElseIf ComboBox1.Text = "Miles to Kilometers" Then
            ' Perform Miles to Kilometers conversion
            convt = Double.Parse(TextBox1.Text) * 1.60934
            Label4.Text = convt & " Kilometers"
        ElseIf ComboBox1.Text = "Kilometers to Miles" Then
            ' Perform Kilometers to Miles conversion
            convt = Double.Parse(TextBox1.Text) / 1.60934
            Label4.Text = convt & " Miles"
        ElseIf ComboBox1.Text = "Centimeter to Meter" Then
            ' Perform Centimeter to Meter conversion
            convt = Double.Parse(TextBox1.Text) / 100
            Label4.Text = convt & " Meters"
        ElseIf ComboBox1.Text = "Meter to Centimeter" Then
            ' Perform Meter to Centimeter conversion
            convt = Double.Parse(TextBox1.Text) * 100
            Label4.Text = convt & " Centimeters"
        ElseIf ComboBox1.Text = "Celcious to Kelvin" Then
            ' Perform Celsius to Kelvin conversion
            convt = Double.Parse(TextBox1.Text) + 273.15
            Label4.Text = convt & " Kelvin"
        ElseIf ComboBox1.Text = "Kelvin to Celcious" Then
            ' Perform Kelvin to Celsius conversion
            convt = Double.Parse(TextBox1.Text) - 273.15
            Label4.Text = convt & " Celcious"
        ElseIf ComboBox1.Text = "Choose one....." Or TextBox1.Text = "" Then
            ' Show a message if no conversion is selected or no input is provided
            MessageBox.Show("Select a Unit conversion", "Unit Calculator", MessageBoxButtons.OK, MessageBoxIcon.Information)
        End If
    End Sub
End Class