hi everybody i just need to know what is the function of  preg_split 
and that which is inside of  brackets:

$keywords = preg_split ('/[\s]+/',$keywords);

Split a string into an array, split at every one or more whitespace. See the manual.

commented: thnx for your help +2

  " ", \r, \t, \n and \f

  what this mean,sory but i wont a better explain 

"\n" -> new line
"\t" -> tab
"\r" -> carriage return


but i wont a better explain

pritaes is well respected, and has taken time to help you. You clearly have not checked google, nor the search function on this web site.

All of what you are "wanting a better explaination" on is very easily searched via google. You seem to lack a basic understanding of "DO NOT BIT THE HAND THAT FEEDS".

I have watched the last few threads of yours and it appears you have ripped someone elses code and quite clearly do not know how it functions. Have you actually thought of contacting the individual that created it the first time round?

all of you are to good here :)