Get extension from a file which is has not extension

Question

is there any method to get (actually guess!) the extension file? in my program, somewhere I get a file which the application analyze it for understanding is it ZIP or MOV.

I found out this, but it does not support MOV and ZIP.

Update:

By creating a text file which contains the first 8 bits of the file signatures. and the below code, I can determine every file which has no extension. this page could be a good reference.

        string rootPath = $"{name}";
        using (FileStream fsSource = new FileStream(rootPath, FileMode.Open, FileAccess.Read))
        {
            byte[] fileBytes = new byte[8]; // the number of bytes you want to read
            fsSource.Read(fileBytes, 0, 8);

            /*
             zip = 50-4B-03-04-0A-00-00-00
             mov = 00-00-00-20-66-74-79-70
             html = 3C-21-64-6F-63-74-79-70
             rar 1 = 52-61-72-21-1A-07
             rar 5 = 52-61-72-21-1A-07 

            */
            string filestring = BitConverter.ToString(fileBytes);
            // string filestring = Encoding.UTF8.GetString(fileBytes); 
            File.WriteAllText($"{DownloadPath}\\filestring.txt", filestring);
        }

Read up on those file formats. Then open the files and examine the structure to figure out the type. — 001, Aug 02 '18 at 12:59
A file extension is just some text. Do you actually mean the file type? — Ňɏssa Pøngjǣrdenlarp, Aug 02 '18 at 12:59
@Adriani6 It's actually not uncommon at all, especially for files in Unix or from programs heavily associated with Unix. — mason, Aug 02 '18 at 13:04
A file does not have to have an extension. You can check its header to determine its type. Formats like ZIP and MOV are well defined, you can find their header info on the internet. — Cetin Basoz, Aug 02 '18 at 13:05
[This could help you](https://stackoverflow.com/questions/58510/using-net-how-can-you-find-the-mime-type-of-a-file-based-on-the-file-signature) — FakeCaleb, Aug 02 '18 at 13:07

score 5 · Accepted Answer · edited Aug 02 '18 at 13:28

5

Just read the header section of the file (several bytes at the beginning of the file) and you can detect its format.

For example this page has information about mov files.

You can read file header like this code (here I have assumed that reading 4 bytes will be enough, however, you can change it as you like if you need more/less bytes to determine the format):

 using (FileStream fsSource = new FileStream(pathSource, FileMode.Open, FileAccess.Read))
 {
     byte[] bytes = new byte[4]; // the number of bytes you want to read
     fsSource.Read(bytes, 0, 4);
 }

edited Aug 02 '18 at 13:28

Wai Ha Lee

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answered Aug 02 '18 at 13:09

Ashkan Mobayen Khiabani

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Thanks, actually it is yours! and I just want to fix its bugs! – joei Aug 02 '18 at 13:15
1

what about `4-letter` extension files? – Gonzalo Lorieto Aug 02 '18 at 13:35
@GonzaloLorieto, we are not talking about extensions here, we open the file and read 4 (in here) first bytes of the file and determine if the file extension should be mov, zip, or something else – Ashkan Mobayen Khiabani Aug 02 '18 at 13:36
1

I missread. Good solution.My apologies – Gonzalo Lorieto Aug 02 '18 at 13:41
@GonzaloLorieto You are very welcome. – Ashkan Mobayen Khiabani Aug 02 '18 at 13:42

Get extension from a file which is has not extension

1 Answers1