RegEx - Chk for special chars

I want to check a string only contains a-z 0-9 ( ) . and #

I've used

ereg("^[a-zA-z0-9().#]*)$"),$instr)

which parses a string correctly until I try and parse a !,",£,$ ... or any
of the other special/reserved characters.

First q: what am I doing wrong
Second q: is there clarification on whether characters need to be escaped
when part of a regex statement? i.e., should it be [$] or [\$] - some
websites/posts state they should be escaped, others say they shouldn't


Thanks

Matt


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