How to extract domain from string with regex?

[deko]

I'm sure someone has passed this way before...

I want to check to see is a domain name is contained in a string, and if one is,
I want to extract it. In these strings, domains are always preceded by
"http://" or "http : //www" (without the spaces).

in pseudo code, I thought it might look like this:

if (eregi("http: //", $mystring))
{
$domain = explode("http: //", $mystring);
$domain = array_reverse($ domain);
}
$parts = domain[0];
explode(".", $parts);
if ($parts[0] == "www")
{
$extracted = $parts[1]."."$parts[2];
}
else
{
$extracted = $parts[0]."."$parts[1];
}

Does this look about right?

Thanks in advance.

[deko]

Re: How to extract domain from string with regex?

here's a cleaner example:

if (eregi("http://", $mystring))
{
$mystring = explode("http://", $mystring);
$mystring = array_reverse($ mystring);
$domain = $mystring[0];
$domain = explode(".", $domain);
if ($domain[0] == "www")
{
$extracted = $domain[1].".".$domain[2];
}
else
{
$extracted = "$domain[0].".".$domain[1];
}
}

Can I egrep on "http://" ? or do I need to escape the "/" ?

[Alvaro G. Vicario]

Re: How to extract domain from string with regex?

*** deko escribió/wrote (Fri, 25 Aug 2006 23:09:28 -0700):

In these strings, domains are always preceded by
"http://" or "http : //www" (without the spaces).

Without the spaces? Then, why do you add the spaces?

Given that precondition, I wouldn't use regex:

parse_url Parse a URL and return its components

usage:
array parse_url ( string url )

Parameters
url
The URL to parse

Return Values
On seriously malformed URLs, parse_url() may return FALSE and emit a
E_WARNING. Otherwise an associative array is returned, whose components may
be (at least one):

scheme - e.g. http
host
port
user
pass
path
query - after the question mark ?
fragment - after the hashmark #

in pseudo code, I thought it might look like this:
>
if (eregi("http: //", $mystring))

Sorry, but I just can't understand all that story about spaces/not spaces
:-?



--
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++ Mi sitio sobre programación web: http://bits.demogracia.com
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--

[deko]

Re: How to extract domain from string with regex?

Thanks for the tip on parse_url.

But I still have to find the URL (which could be anywhere) in the string.

Without the spaces? Then, why do you add the spaces?

Here's a psuedocode example without the spaces:

if (eregi("http://", $mystring))
{
$mystring = explode("http://", $mystring);
$mystring = array_reverse($ mystring);
$domain = $mystring[0];
$domain = explode(".", $domain);
if ($domain[0] == "www")
{
$extracted = $domain[1].".".$domain[2];
}
else
{
$extracted = "$domain[0].".".$domain[1];
}
}

Would it be better to use preg_match here?

preg_match('@^( ?:http://)?([^/]+)@i',
"http://www.php.net/index.html", $matches);
$host = $matches[1];

// get last two segments of host name
preg_match('/[^.]+\.[^.]+$/', $host, $matches);
echo "domain name is: {$matches[0]}\n";

But would this work if the URL is buried in a string?