How to get the file extension from a url?

Question

New to ruby, how would I get the file extension from a url like:

http://www.example.com/asdf123.gif

Also, how would I format this string, in c#

Answer 1

Use File.extname

File.extname("test.rb")         #=> ".rb"
File.extname("a/b/d/test.rb")   #=> ".rb"
File.extname("test")            #=> ""
File.extname(".profile")        #=> ""

To format the string

"http://www.example.com/%s.%s" % [filename, extension]

Answer 2

I realize this is an ancient question, but here's another vote for using Addressable. You can use the .extname method, which works as desired even with a query string:

 Addressable::URI.parse('http://www.example.com/asdf123.gif').extname # => ".gif"
 Addressable::URI.parse('http://www.example.com/asdf123.gif?foo').extname # => ".gif"

Answer 3

url = 'http://www.example.com/asdf123.gif'
extension = url.split('.').last

Will get you the extension for a URL(in the most simple manner possible). Now, for output formatting:

printf "http://www.example.com/%s.%s", filename, extension

Answer 4

You could use Ruby's URI class like this to get the fragment of the URI (i.e. the relative path of the file) and split it at the last occurrence of a dot (this will also work if the URL contains a query part):

require 'uri'
your_url = 'http://www.example.com/asdf123.gif'
fragment = URI.split(your_url)[5]

extension = fragment.match(/\.([\w+-]+)$/)

Answer 5

This works for files with query string

file = 'http://recyclewearfashion.com/stylesheets/page_css/page_css_4f308c6b1c83bb62e600001d.css?1343074150'
File.extname(URI.parse(file).path) # => '.css'

also returns "" if file has no extension