Stupid Problem, with Replace

Im taking a VB class and cant figure out how to get it to replace more than one character this is my code.

VB Code:

Option Explicit On 
Option Strict On
 
Public Class JacobsonForm
    Inherits System.Windows.Forms.Form
 
    Private Sub uiExitButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles uiExitButton.Click
        'ends the application
        Me.Close()
    End Sub
 
    Private Sub uiDisplayButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles uiDisplayButton.Click
        Dim oldpass As String = Me.uiOldPassTextBox.Text
        Dim oldpassnumber As Double
        Dim newpass As String
        Dim i As Integer = 0
 
 
        oldpassnumber = oldpass.Length
        If oldpassnumber >= 5 AndAlso oldpassnumber < 8 Then
 
            Do Until i = oldpassnumber
                newpass = oldpass.Replace("A", "X")
                newpass = oldpass.Replace("E", "X")
                newpass = oldpass.Replace("I", "X")
                newpass = oldpass.Replace("O", "X")
                newpass = oldpass.Replace("U", "X")
                i = i + 1
            Loop
        End If
 
        Me.uiNewPassLabel.Text = newpass
 
 
 
 
    End Sub
End Class

what am i missing i tried to get it to loop, but it only does the U, how can i get to do them all?

I don't see why you are looping at all. Calling .Replace will replace all instances of the character in the string, so why do the loop?

In regards to your question about it only replacing one of them, it is because you are calling replace on the original oldpass string, and not changing the oldpass string at all, so it replaces the character each time, but then on the next line, it goes back to the original pass and then just switches one character, so it will only show the last replace call. To fix it, just assign the replace to the same "oldpass" variable, and that should do it, without having to loop at all.

VB Code:

Dim oldpass As String = "XAXEXIXOXU"
        oldpass = oldpass.Replace("A", "X")
        oldpass = oldpass.Replace("E", "X")
        oldpass = oldpass.Replace("I", "X")
        oldpass = oldpass.Replace("O", "X")
        oldpass = oldpass.Replace("U", "X")
        MessageBox.Show(oldpass)

If you set a breakpoint in your code above that was giving you problems and step line by line, or place a messagebox in between each call displaying the newpass variable, you will see what was going on.