Question

I currently have this but it’s not flawless:

$testcases = array(
array("I love mywebsite.com", true),
array("mywebsite.com/ is what I like", true),
array("www.mywebsite.com is my website", true),
array("Check out www.mywebsite.com/", true),
array("... http://mywebsite.com ...", true),
array("... http://mywebsite.com/ ...", true),
array("... http://www.mywebsite.com ...", true),
array("... http://www.mywebsite.com/ ...", true),
array("I like commas and periods. Just like www.mywebsite.com, they do it too!", true),
array("thisismywebsite.com is a lot better", false),
array("The URL fake.mywebsite.com is unknown to their server", false),
array("Check out http://redirect.mywebsite.com/www.ultraspammer.com", false)
);

function contains_link($text) {
return preg_match("/(https?:\/\/(?:www\.)?|(?:www\.))mywebsite\.com/", $text) > 0;
}

foreach ($testcases as $case) {
echo $case[0] . "=".(contains_link($case[0]) ? "true" : "false") . " and it should be " . ($case[1] ? "true" : "false") . "<br />";
}

Output:

I love mywebsite.com=false and it should be true
mywebsite.com/ is what I like=false and it should be true
www.mywebsite.com is my website=true and it should be true
Check out www.mywebsite.com/=true and it should be true
... http://mywebsite.com ...=true and it should be true
... http://mywebsite.com/ ...=true and it should be true
... http://www.mywebsite.com ...=true and it should be true
... http://www.mywebsite.com/ ...=true and it should be true
I like commas and periods. Just like www.mywebsite.com, they do it too!=true and it should be true
thisismywebsite.com is a lot better=false and it should be false
The URL fake.mywebsite.com is unknown to their server=false and it should be false
Check out http://redirect.mywebsite.com/www.ultraspammer.com=false and it should be false

Answer 1

An alternative to regex: parse_url()

$url = parse_url($text);
if($url['host'] == 'www.mywebsite.com' || $url['host'] == 'mywebsite.com')

UPDATE:

Assuming that $text can have a lot of domains,use strstr() instead.

if(strstr($text,"mywebsite.com") !== FALSE)

UPDATE 2:

function contains_link($text) {
        return preg_match("/(^(https?:\/\/(?:www\.)?|(?:www\.))?|\s(https?:\/\/(?:www\.)?|(?:www\.))?)mywebsite\.com/", $text);
}

and:

  contains_link("AAAAAAA http://mywebsite.com"); //1
  contains_link("foo BAaa http://www.mywebsite.com"); //1
  contains_link("abc.com www.mywebsite.com"); // 1