Regex Question: Get Filename Without Extension in One Shot?In

Question

I want to get just the filename using regex, so I've been trying simple things like

([^\.]*)

which of course work only if the filename has one extension. But if it is adfadsfads.blah.txt I just want adfadsfads.blah. How can I do this with regex?

In regards to David's question, 'why would you use regex' for this, the answer is, 'for fun.' In fact, the code I'm using is simple

length_of_ext = File.extname(filename).length
filename = filename[0,(filename.length-length_of_ext)]

but I like to learn regex whenever possible because it always comes up at Geek cocktail parties.

Answer 1

Everything followed by a dot followed by one or more characters that's not a dot, followed by the end-of-string:

(.+?)\.[^\.]+$

The everything-before-the-last-dot is grouped for easy retrieval.

If you aren't 100% sure every file will have an extension, try:

(.+?)(\.[^\.]+$|$)

Answer 2

how about 2 captures one for the end and one for the filename.

eg.

(.+?)(?:\.[^\.]*$|$)

Answer 3

Try this:

(.+?)(\.[^.]*$|$)

This will:

• Capture filenames that start with a dot (e.g. ".logs" is a file named ".logs", not a file extension), which is common in Unix.
• Gets everything but the last dot: "foo.bar.jpeg" gets you "foo.bar".
• Handles files with no dot: "secret-letter" gets you "secret-letter".

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Note: as commenter j_random_hacker suggested, this performs as advertised, but you might want to precede things with an anchor for readability purposes.

Answer 4

Ok, I am not sure why I would use regular expression for this. If I know for example that the string is a full filepath, then I would use another API to get the file name. Regular expressions are very powerfull but at the same time quite complex (you have just proved that by asking how to create such a simple regex). Somebody said: you had a problem that you decided to solve it using regular expressions. Now you have two problems.

Think again. If you are on .NET platform for example, then take a look at System.IO.Path class.

Answer 5

I have a similar problem using Apache.

In my .htaccess file I'd like to convert requests like this:

url/portfolio/filename.htm

to:

url?filename

Any takers?