Using a Regex to extract the domain from a URL

Ruby
#1

Hi guys,

I’m having some problems on good old Codewars, writing a method that can
take a URL and return just the domain.

I’ve managed to create a Regex in Rubular
(http://rubular.com/r/C7wAZRq8OA)
that passes my tests, but I’m having trouble implementing it properly.

Here are my tests:
Test.assert_equals(domain_name(“http://github.com/carbonfive/raygun”),
“github”)
Test.assert_equals(domain_name(“http://www.zombie-bites.com”),
“zombie-bites”)
Test.assert_equals(domain_name(“https://www.cnet.com”), “cnet”)

Here’s my method:
def domain_name(url)
url.match(/https*://w*.(\w-\w)./)
end

As far as I can tell, this should work. Any ideas on what I’m doing
wrong?
Thanks!

#2

Hello,

On 5 Ιουν 2014, at 17:03 , Adam W. [email protected] wrote:

Here’s my method:
def domain_name(url)
url.match(/https*://w*.(\w-\w)./)
end

As far as I can tell, this should work. Any ideas on what I’m doing wrong?
Thanks!

I tested your code and returns ‘https://’ too, so your regexp is wrong:

$ cat test.rb&& ruby test.rb

def domain_name(url)
puts url.match(/https*://w*.(\w-\w)./).to_s
end

list = %w{https://github.com/carbonfive/raygun
http://www.zombie-bites.com https://www.cnet.com}

list.each {|x| domain_name(x)}

=> https://github.
=> http://www.zombie-bites.
=> https://www.cnet.

You could adjust the regexp to match a given set of domains domain
names[1]. But the problem is unsolvable using regular expressions[2]. In
theory you should create a list with all the available domain names,
(maybe a google search will even give you a TXT file) and then write a
complicate set of instructions to match those. Only this way you might
get a complete solution IMHO.

Best regards,

[1]
http://stackoverflow.com/questions/12772423/regex-match-main-domain-name

[2] http://stackoverflow.com/a/12772473/577133

Panagiotis (atmosx) Atmatzidis

email: [email protected]
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#3

/^https?://(www.)?[a-zA-Z0-9_-]*.(com|net|org)/?((([a-zA-Z/0-9_-])+)?)$/