How To Check If Item Already Exists In TXT File

Mar 2, 2012

The following code will save an item to file over and over again, but how do I save an item only once?
Dim w As New IO.StreamWriter("E:est.txt", True)
w.WriteLine(ListBox1.SelectedItem, True)
w.Close()

If, for example, number1 is already saved in the txt file then how do I not save it again, using something like the following?
dim exist As IO.FileAccess ("e:s.txt")
if exist.that.item.is.exist= true then
w.WriteLine(ListBox1.SelectedItem, True)
[Code] .....
I am using VS 2010.

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[Code]...

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