Unzip One File from Zip without Overwriting Existing File

Download Chilkat .NET for 2.0 / 3.5 Framework

Download Chilkat .NET for 1.0 / 1.1 Framework

Locate and unzip a single file within a .zip, checking first to see if the file already exists before unzipping.

        ' This must be called once at the beginning of your program.
        zip.UnlockComponent("Anything for 30-day trial")

        ' Open a zip archive.
        Dim success As Boolean
        success = zip.OpenZip("myZip.zip")
        If (Not success) Then
            MessageBox.Show(zip.LastErrorText)
            Exit Sub
        End If

        ' Find the file to be unzipped.
        Dim entry As Chilkat.ZipEntry
        ' In this case, we know that test.txt is in a sub-directory within the zip.
        entry = zip.FirstMatchingEntry("*/test.txt")

        ' Does test.txt already exist in our current working directory?
        Dim f As New System.IO.FileInfo("test.txt")
        If (Not f.Exists) Then
            ' Extract into the current working directory, regardless of the path
            ' in the Zip.
            entry.ExtractInto(".")
        End If

        zip.CloseZip()