How can I display a name in a different sequence using strings? - vb.net

Question

I'm having trouble with a problem that I was assigned for my Visual Basic 2012 class. The instructions are below. So far, I have it displaying only the first name entered, and nothing else. How can I make it to display both the first name and the last name in the sequence requested?
String Problem: Enter your first and last name in a text box. Take the name and display it in a label box showing the last name, first name.
Text Box Entry: Jane Doe
Label Box: Doe, Jane
The code I have so far is below. Thanks for any help!
Private Sub btndisplay_Click(sender As Object, e As EventArgs) Handles btndisplay.Click
Dim fullname As String
Dim firstname As String
Dim indexnum As Integer
Dim lastname As String
fullname = fulltextbox.Text
indexnum = fullname.IndexOf(" ")
firstname = fullname.Substring(0, indexnum)
firstlabel.Text = firstname
fulltextbox.Focus()
End Sub
Private Sub fulltextbox_TextChanged(sender As Object, e As EventArgs)
firstlabel.Text = String.Empty
fulltextbox.SelectAll()
End Sub
Private Sub btnexit_Click(sender As Object, e As EventArgs) Handles btnexit.Click
Me.Close()
End Sub

Answer 1

You are on the right track by first determining where the space is located:
indexnum = fullname.IndexOf(" ")
Now based on this index, you can split the string into two strings, firstname and lastname:
firstname = fullname.Substring(0, indexnum)
lastname = fullname.Substring(indexnum+1)
You need to use indexnum+1, instead of indexnum, otherwise you will include the spacing character.
Finally you group them together again by using the string concatenation operator (&):
firstlabel.Text = lastname & ", " & firstname
The final method thus looks like:
Private Sub btndisplay_Click(sender As Object, e As EventArgs) Handles btndisplay.Click
Dim fullname As String
Dim firstname As String
Dim indexnum As Integer
Dim lastname As String
fullname = fulltextbox.Text
indexnum = fullname.IndexOf(" ")
firstname = fullname.Substring(0, indexnum)
lastname = fullname.Substring(indexnum+1)
firstlabel.Text = lastname & ", " & firstname
fulltextbox.Focus()
End Sub

Answer 2

Note, this won't work if your using middle initials. Also, I would remove fulltextbox.SelectAll() from fulltextbox_TextChanged
Private Sub btndisplay_Click(sender As Object, e As EventArgs) Handles btndisplay.Click
Dim Names() As String = fulltextbox.Text.Split(" "c)
If Names.Count = 2 Then
firstlabel.Text = Names(1) + ", " + Names(0)
ElseIf Names.Count = 0 Then
MessageBox.Show("Please enter name.")
Else
MessageBox.Show("Invalid Nmae entered.")
End If
fulltextbox.Text = ""
End Sub