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| Title | Read and write all of the lines in a text file in Visual Basic .NET |
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| Description | This example shows how to read and write all of the lines in a text file in Visual Basic .NET. It uses the System.IO.File.ReadAllLines and System.IO.File.WriteAllLines methods. |
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| Keywords | sort, IComparer, file, compare, Visual Basic .NET |
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| Categories | Files and Directories |
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This example doesn't really do much that's useful. It's just intended to remind you that the ReadAllLines and WriteAllLines methods exist.
The System.IO.File class provides methods to read and write all of the lines in a file to and from an array of strings. (This really should have been included in the My namespace along with My.Computer.FileSystem.ReadAllText and My.Computer.FileSystem.WriteAllText.)
When you click the program's ReadLines button, the following button reads the file's lines into the array all_lines. It then displays them in a ListBox just so you can see that something happened.
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Private Sub btnReadLines_Click(ByVal sender As _
System.Object, ByVal e As System.EventArgs) Handles _
btnReadLines.Click
Dim all_lines() As String = _
System.IO.File.ReadAllLines(txtInputFile.Text)
lstItems.DataSource = all_lines
End Sub
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When you click the Write Lines button, the following code calls the WriteAllLines method to save the lines in the ListBox into an output file.
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Private Sub btnWriteLines_Click(ByVal sender As _
System.Object, ByVal e As System.EventArgs) Handles _
btnWriteLines.Click
System.IO.File.WriteAllLines(txtOutputFile.Text, _
lstItems.DataSource)
Beep()
End Sub
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