Lesson 12: Mastering String Manipulation in VB2022

' Using the + operator with mixed types
Dim str1 = "Visual ", str2 = "Basic ", str3 = "2022", str As String
Dim num As Integer = 100

' This works:
str = str1 + str2 + str3 ' "Visual Basic 2022"

' This causes an error:
' str = str1 + str2 + str3 + num

' Using the & operator with mixed types
str = str1 & str2 & str3 & num ' "Visual Basic 2022100"

Private Sub BtnFormat_Click(sender As Object, e As EventArgs) Handles BtnFormat.Click
    Dim fullName As String = TxtFullName.Text.Trim()
    
    ' Find space position
    Dim spacePos As Integer = InStr(fullName, " ")
    
    If spacePos = 0 Then
        MessageBox.Show("Please enter first and last name separated by a space")
        Return
    End If
    
    ' Extract parts
    Dim firstName As String = Microsoft.VisualBasic.Left(fullName, spacePos - 1)
    Dim lastName As String = Microsoft.VisualBasic.Right(fullName, Len(fullName) - spacePos)
    
    ' Format based on selection
    Select Case cmbFormat.SelectedIndex
        Case 0 ' First Last
            LblResult.Text = firstName & " " & lastName
        Case 1 ' Last, First
            LblResult.Text = lastName & ", " & firstName
        Case 2 ' F. Last
            LblResult.Text = Microsoft.VisualBasic.Left(firstName, 1) & ". " & lastName
        Case 3 ' Last F.
            LblResult.Text = lastName & " " & Microsoft.VisualBasic.Left(firstName, 1) & "."
    End Select
End Sub

Private Sub BtnGenerate_Click(sender As Object, e As EventArgs) Handles BtnGenerate.Click
    Dim length As Integer
    
    ' Validate length input
    If Not Integer.TryParse(TxtLength.Text, length) Or length < 8 Or length > 20 Then
        MessageBox.Show("Please enter a valid password length (8-20)")
        Return
    End If
    
    ' Character sets
    Dim lower As String = "abcdefghijklmnopqrstuvwxyz"
    Dim upper As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    Dim digits As String = "0123456789"
    Dim symbols As String = "!@#$%^&*()_-+=[]{}|;:,.<>?/"
    Dim allChars As String = lower & upper & digits & symbols
    
    Dim password As String = ""
    Dim rnd As New Random()
    
    ' Generate password
    For i As Integer = 1 To length
        Dim index As Integer = rnd.Next(0, Len(allChars))
        password &= Mid(allChars, index + 1, 1)
    Next
    
    ' Ensure at least one of each character type
    If InStr(password, "A") < "a" Then ' Case-insensitive check
        password = Mid(password, 1, 1) & Chr(rnd.Next(65, 91)) & Mid(password, 3)
    End If
    
    ' Display result
    TxtPassword.Text = password
End Sub