Rewrite a url in a string http://www. ???

Hi,

I have a string that will contain a URL, this url will eventually be processed and needs to be in the format:

http://www.

how would i check if it is written differently and rewrite it to that format if it is different...

for example someone enters http://www.google.com/ the script does nothing.

someone enters www.google.com/ the script adds http://

someone enters http://google.com/ the script adds www.

someone enters google.com/ the script adds http://www.

is there any premade/easy ways to do this, or if you have a function that you have made that would be great...

You should research the power of regular expressions. http://us2.php.net/manual/en/ref.pcre.php

That in combination with a few clever if/else or case statements should do the job.

<?php

function url_checker($url)
{
if (substr($url,0,11) == "http://www.")
return $url;
else
{
if (substr($url,0,7) == "http://")
return "http://www." . substr($url,7,strlen($url) - 7);
else
return "http://www." . $url;
}
}

?>

No need for the strlen() call, the remainder of the string is assumed if the third parameter is omitted:

function format_url( $url )
{
while ( strtolower( substr( $url, 0, 7 ) ) == 'http://' )
{
$url = substr( $url, 7 );
}
while ( strtolower( substr( $url, 0, 4 ) ) == 'www.' )
{
$url = substr( $url, 4 );
}
return 'http://www.' . $url;
}


Or using a single RegExp:

function format_url( $url )
{
return 'http://www.' . preg_replace( '/^(\w+\:\/\/)*(www\.)*/i', '', $url );
}

...note that this will replace any protocol, ie: http://, ftp://, foo://, etc...