php - Storing a piece of the string for later use in replacement -

It is not certain that the subject was clear, it is difficult to describe, easy to show:

It needs change:

  $ text = '% textgroup% img_green% img_Red and some more text here';  

To do this:

  $ text = 'bunch of text & lt; Img src = "/ assets / images / green.gif" alt = "green" / & gt; & Lt; Img src = "/ assets / images / Red.gif" alt = "red" /> And some more text here ';  

Thanks in advance.

  $ text = preg_replace ('/% img _ (\ W +) / ',' & lt; img src = "/ assets / images / \ 1.jpg" alt = "\ 1" /> ", $ text);  

Check how it's working