Regular Expressions..

Hey I am creating an online web tool using PHP and am stuck with some concepts of Regular expressions. The problem starts like this, I have to get input of special characters like " [ ] { } - ( ) < > " all these have some specialty inside the programming logic, but my major issue is that, I cant capture these symbols using regular expression , can anyone help me in coding the regex part so that I can capture these symbols., It ll be helpful if anyone can jus do for capturing these symbols.. I also have another doubt do PHP have functions for Probability and Permutation and Combinations etc ?? Relp Asap.., Naresh..