[Charter]

>> working only if link contain only one pair of []

So it works in example but not with PhpDig? What's a link to a page containing multiple [ ] in its links?

>> first regexp doesn't needed becourse site have'nt frames

Other people might have frames though.

The RFC2732 protocol states in part:

   (3) Add "[" and "]" to the set of 'reserved' characters:

      reserved    = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" |
                    "$" | "," | "[" | "]"

   and remove them from the 'unwise' set:

      unwise      = "{" | "}" | "|" | "\" | "^" | "`"

Sometimes using reserved characters in links, other than for their intended purpose, can cause problems as was the case in this thread (colon used outside of <user>:<pass>@<host>:<port> meaning so the PHP parse_url function did not understand).

You might want to consider encoding your URIs according to this rather than use literal square brackets in your links.