Use Console.Write method.
Public Class MainClass Public Shared Sub Main() Dim lineInput As String lineInput = "a\ta\ta\taa" While Not lineInput Is Nothing Dim fields() As String = lineInput.Split(ControlChars.Tab) Dim isFirstField As Boolean = True Dim item As String For Each item In fields If isFirstField Then isFirstField = False Else Console.Write(",") End If Next item lineInput = Console.ReadLine() End While End Sub End Class