php - Regex: Get // line but not if start with http://

Question

I need a Regex to get //, but if it starts with http:// for it to do nothing.

Example:

<?php 
function lol(){
// blabalbal
} // catch'm all

echo 'http://link.com.br'; // this is a link.

Need to catch:

// blabalbal line

// catch'm all line (starting on "// catch")

// this is a link (starting on "// this").

I was trying with variations of: '///(.*)$'

Answer 1

You can use a negative lookbehind which php supports.

(?<!http:)(//.*)

This will only match // if it is not preceded by http:. You may be able to get away with just : depending on your needs.