I’m trying to replace a string in PHP which is not a link.

Example:

<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean mattis sodales viverra. Pellentesque feugiat diam quis nisl commodo quis dignissim justo posuere. <a href=”http://d-media.nl/stringtolookfor“>Donec</a> a est turpis, vel eleifend magna. In vitae dictum lorem. Curabitur vel adipiscing purus.</p>

<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean stringtolookfor mattis sodales viverra. Pellentesque feugiat diam quis nisl commodo quis dignissim justo posuere. Donec a est turpis, vel eleifend magna. In vitae dictum lorem. Curabitur vel adipiscing purus.</p>

I would like to find the first occurence of ‘stringtolookfor’ which is not part of a link (thus within <a href=””>)