Suppose I only want user to type in url starts with http://www.google.com What is the regular expression for this?
Thanks!
4 Answers
Just get the substring from 0 to the length of http://www.google.com and you're done.
answered Nov 27, 2010 at 1:49
Niet the Dark Absol
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Comments
Rather than use a regex, you might want to consider using the URI library that comes with Ruby. It's made to take apart and build URLs, is well tested, and less error-prone than trying to reinvent the same functionality.
require 'uri'
url = URI.parse('http://www.google.com/path/to/page.html?a=1&b=2')
url.scheme # => "http"
url.host # => "www.google.com"
url.path # => "/path/to/page.html"
url.query # => "a=1&b=2"
If that's not good enough, the Addressable::URI gem is even more capable.
Comments
Try this:
/\Ahttp:\/\/www\.google\.com(.*)?\Z/
ruby-1.9.2-p0 > "http://www.google.com" =~ /\Ahttp:\/\/www\.google\.com(.*)?\Z/
=> 0
ruby-1.9.2-p0 > "http://www.google.com/foobar" =~ /\Ahttp:\/\/www\.google\.com(.*)?\Z/
=> 0
ruby-1.9.2-p0 > $1
=> "/foobar"
Comments
Rails has a convenient start_with? method for this. If it's just a static string, no regular expression is needed.
url.start_with?("http://www.google.com")
