which regexp require preg_grep() and which can be used with ereg()?

In Perl I used "/\S/" to check for blank lines read from a file. Now I'm learning PHP. How do I know what is a 'standard' regexp that ereg() can handle and how do I know what is Perl-specific syntax so that I must use preg_grep() instead? For example, can I use ereg("\S",$buffer) to check for a blank or must I use preg_grep()or that. What specific things require preg_grep() to be used instead of ereg()? Thanks. -- John A. Grant * I speak only for myself * (remove 'z' to reply) Radiation Geophysics, Geological Survey of Canada, Ottawa If you followup, please do NOT e-mail me a copy: I will read it here