[PHP] regular expression

[George Lantz]

Could someone help me with a regular expression? I am not very good at
them. I want to find the following pattern inside a file:
 
 [%string%]
 
Then extract the string portion to store in array.  I would next like to
replace those patterns with html code. That's right you guessed it a
template engine type program.
 
I thought it was"/\[\%[a-z]\%\]" but I guess I am wrong. Then what
function do I use to extract.
 
Thank you,
George