hi, i am currently doing a java simple calculator parser, that will deal very simply with + and - operators only and numbers only and also ( and ) , i have read about
http://scriptasylum.com/tutorials/infix_postfix/algorithms/postfix-evaluation/index.htm
http://scriptasylum.com/tutorials/infix_postfix/algorithms/infix-postfix/index.htm
and i am wondering if the brackets can be applied to the above mentioned way of creating a calculator parser?
The beauty of the postfix/prefix notation is that you do NOT need the brackets. Brackets are used in infix notation because there are ambiguities, e.g:
a + b - c
This can mean either of the following:
(a + b) - c
a + (b - c)
However, in postfix notation, they are clearly different:
a b + c -
a b c - +
There is no need for parantheses/brackets to enforce evaluation order in postfix notation.
You can take an expression in infix notation with parantheses and convert it to postfix notation, obeying operator precedence. One such algorithm is Edsger Dijkstra's stack-based "shunting-yard algorithm".
If you are only concerned with the simple math operators + and - which are commutative then you probably do not need to care about parenthesis which usually enforce the order of computation.
Your calculator might only need to be a simple parser and accumulator that ignores parenthesis if present - unless I'm missing something about the intended meaning of the parenthesis