Including mathematical symbols in STRING token

[pkthakur]

Hi,
    I am working on a parser in which STRING token consists of all the
possible characters, like =,/,+ etc. But these are also needed to be
taken as having its usual meaning (mathematical operators, etc). What
is the best method to get the desired result. Is it necessary to use
only quoted strings (between " ") or we can do with usual unquoted
strings ?

Any suggestion regarding this would be of great help.

Thanking you all,
praveen