Get File Extension of File Dropped Onto Windows Form

Question

How can I capture the file extension of the file dropped onto a windows form? For example (pseudocode below)

if extension = .xlsx { method1 }
if extension = .txt { method2 }
else { MessageBox.Show("Please drag/drop either a .xlsx or a .txt file"); }

here you can find your answer with a simple google search [Get File Extension](https://msdn.microsoft.com/en-us/library/system.io.path.getextension%28v=vs.110%29.aspx) please show a little bit more effort — MethodMan, Apr 06 '15 at 19:05
possible duplicate of [How do I drag and drop files into a C# application?](http://stackoverflow.com/questions/68598/how-do-i-drag-and-drop-files-into-a-c-sharp-application) — FreeAsInBeer, Apr 06 '15 at 20:50

score 3 · Accepted Answer · edited May 23 '17 at 10:29

You have to keep in mind that the user can drag more than a single file. Use this code as a starting point. First thing you want to do is modify the DragEnter event handler so the user simply can't drop the wrong kind of file at all:

    private void Form1_DragEnter(object sender, DragEventArgs e) {
        if (!e.Data.GetDataPresent(DataFormats.FileDrop)) return;
        string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
        foreach (var file in files) {
            var ext = System.IO.Path.GetExtension(file);
            if (ext.Equals(".xlsx", StringComparison.CurrentCultureIgnoreCase) ||
                ext.Equals(".txt",  StringComparison.CurrentCultureIgnoreCase)) {
                e.Effect = DragDropEffects.Copy;
                return;
            }
        }
    }

The DragDrop event handler is much the same, instead of assigning e.Effect you process the file, whatever you want to do with it.

Get File Extension of File Dropped Onto Windows Form

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