Re: PHP Regular expression help

If you use mine, do the right thing & change all references to
"domain.com" to "example.com", as you're supposed to.

Also, sorry about the line breaks.
Daniel J. Post

On Mon, 21 Mar 2005 15:32:12 -0600, Daniel J. Post
<danieljpost-Re5JQEeQqe8AvxtiuMwx3w@xxxxxxxxxxxxxxxx> wrote:
> I've seen and used weirder and more obfuscated, but nothing more
> complex than this one. I worked it out by hand using the RFCs. It is
> probably not complete, but was as close as I could stand to get it.
> 
> // returns false if URL contains spaces or illegal characters.
> // ignores the http:// (programming should strip or require)
> // second parameter is whatever you want to return if $val is empty
> function djp_is_valid_url($val,$allow_empty=0)
> {
>     if ($val)
>       {
>         $http='http(s)?://'; // http(s) is optional.
> 
>         // usernames and passwords, theoretically can be transmitted
> thru the url,
>         // as username:password-9IKiO1iGCm/QT0dZR+AlfA@xxxxxxxxxxxxxxxx, etc.
>         $userpass='[a-z0-9]{1,}:[a-z0-9]{1,}@';
> 
>         // domain is alphanumeric with hyphens,
>         // any number of iterations, separated by periods.
>         // followed by at least two alphanumeric with hyphens,
>         // followed by a period, then 2-6 alphas (.com, .edu, .tv,
> .net, .museum, et al)
>         $domain='((([0-9a-z-]*\.)*)?[0-9a-z-]{2,})+\.[a-z]{2,6}';
> 
>         // an ip address is 4 numerics delimited by periods.
>         $ip='([0-9]{1,3}.){3}([0-9]{1,3}){1}';
> 
>         // and very optional port #,
>         $port=':[0-9]{1,5}';
> 
>         // with an optional following slash.
>         $slash='/?';
> 
>         // path must start with a slash, followed by optional tilde,
>         // then alphanumeric with underscores, slashes and periods.
>         $path='/(~?[0-9a-z/\._-])*';
> 
>         // "GET" strings. There's an easier way BEGGING to come out of 
> this....
>         $getparams='('.
>           // the first get string starts with ?,
>           // followed by Alphanumeric,'=',optional Alphanumeric or
> %(2hex characters)
>             '(\?[_0-9a-z]{1,}=(([0-9a-z+/_*.-]*)|(%[a-f0-9]{2}))*)*'.
>           // the second and subsequent get parameters start with &,
>           // followed by Alphanumeric,'=',optional Alphanumeric or
> %(2hex characters)
>             '(\&[_0-9a-z]{1,}=(([0-9a-z+/_*.-]*)|(%[a-f0-9]{2}))*)*'.
>         // allow zero or one of the preceding.
>           ')?';
> 
>         $fragment='(#([0-9a-z_.,]*))?';
>         // assemble the parts & check.
> 
> $validurl="^(($http)?(($userpass)?($domain)|($ip))($port)?){1}$slash($path$getparams$fragment)?$";
> // for extra credit, uncomment the next line and read the output
> // print("The regular expression that approximates a valid URL 
> is:\n$validurl");
>         if (eregi($validurl,$val))
>           {
>             return 1;
>           }
>         else
>           {
>             return 0;
>           }
>       }
>     else return $allow_empty;
> }
>