MINI CALCULATOR PROGRAM IN VB.NET

Source code
Public Class frmCalculator
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    End Sub

    Private Sub btnresult_Click(sender As Object, e As EventArgs) Handles btnresult.Click
        If frmvaildate() Then
            Dim fnum, snum, result As Double
            Dim opt As String

            fnum = Double.Parse(txtfnumber.Text)
            snum = Double.Parse(txtsnum.Text)
            opt = txtopt.Text

            Select Case (opt)
                Case "+"
                    result = fnum + snum
                Case "-"
                    result = fnum - snum
                Case "*"
                    result = fnum * snum
                Case "/"
                    If snum = 0 Then
                        MessageBox.Show("No is not  div by zero")
                        Return
                    Else
                        result = fnum / snum
                    End If
                Case Else
                    MessageBox.Show("Invalid Operation")
                    txtopt.Clear()
                    txtopt.Focus()
                    Return
            End Select
            txtresult.Text = result.ToString()
        End If

    End Sub
    Public Function frmvaildate() As Boolean
        Dim flag As Boolean = True
        If (txtfnumber.Text.Length = 0) Then
            MessageBox.Show("Enter First Number")
            txtfnumber.Focus()
            flag = False
        ElseIf Not (IsNumeric(txtfnumber.Text))
            MessageBox.Show("Enter only numeric value")
            txtfnumber.Clear()
            txtfnumber.Focus()
            flag = False
        ElseIf txtsnum.Text.Length = 0
            MessageBox.Show("Enter Second Number")
            txtsnum.Focus()
            flag = False
        ElseIf Not (IsNumeric(txtsnum.Text))
            MessageBox.Show("Enter only numeric value")
            txtsnum.Clear()
            txtsnum.Focus()
            flag = False
        ElseIf txtopt.Text.Length = 0
            MessageBox.Show("Enter Operator")
            txtopt.Focus()
            flag = False
        End If
        Return flag
    End Function
    Private Sub txtfnumber_KeyDown(sender As Object, e As KeyEventArgs) Handles txtfnumber.KeyDown
        If (Integer.Parse(e.KeyCode()) = 13) Then
            txtsnum.Focus()
        End If
    End Sub
    Private Sub txtsnum_KeyDown(sender As Object, e As KeyEventArgs) Handles txtsnum.KeyDown
        If (Integer.Parse(e.KeyCode()) = 13) Then
            txtopt.Focus()
        End If
    End Sub
    Private Sub txtopt_KeyDown(sender As Object, e As KeyEventArgs) Handles txtopt.KeyDown
        If (Integer.Parse(e.KeyCode()) = 13) Then
            btnresult.Focus()
        End If
    End Sub

    Private Sub btnclear_Click(sender As Object, e As EventArgs) Handles btnclear.Click
        clear()
    End Sub
    Public Sub clear()
        txtfnumber.Clear()
        txtsnum.Clear()
        txtopt.Clear()
        txtresult.Clear()
        txtfnumber.Focus()
    End Sub
End Class

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Attendance Management System Program Using Array in Vb.net

Module Module1

    Sub Main()
        Dim studname() As String = {"Rakesh", "Mukesh", "Suresh", "Anil", "Vijay", "Prince"}
        Dim rollno() As Integer = {1001, 1002, 1003, 1004, 1005, 1006}
        Dim attendance(6) As Integer
        Dim counter As Integer = 0
        Dim attenstatus As String
        Dim attencounter As Integer = 0
        Dim totalstudent As Integer = 1
        Dim totabs, totpre As Integer
        totabs = 0
        totpre = 0
        While (totalstudent <= 6)
            Console.Write("Enter Studnet Roll No:-")
            Dim studroll As Integer = Integer.Parse(Console.ReadLine())
            Console.Write(counter)
            For Each studrollno As Integer In rollno
                If studrollno = studroll Then
                    Console.Write("Studnet Name:-" & studname(counter) & vbNewLine)
                    Console.Write("Enter P for Present and A for Absent:-")
                    attenstatus = Console.ReadLine()
                    If (attenstatus = "P") Then
                        attendance(attencounter) = 1
                        attencounter = attencounter + 1
                    ElseIf (attenstatus = "A")
                        attendance(attencounter) = 0
                        attencounter = attencounter + 1
                    End If
                End If
                counter = counter + 1
            Next
            counter = 0
            totalstudent = totalstudent + 1
        End While

        Console.Write("Student Name" & vbTab & "Attendance" & vbNewLine)
        For attendcounter As Integer = 0 To 5
            If attendance(attendcounter) = 0 Then
                totabs = totabs + 1
            ElseIf attendance(attendcounter) = 1
                totpre = totpre + 1
            End If
            Console.Write(studname(attendcounter) & vbTab & vbTab & attendance(attendcounter) & vbNewLine)
        Next
        Console.Write("Total Present Student=" & totpre & vbNewLine & "Total Absent Student=" & totabs)
    End Sub

End Module

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