Equation (expression) parser with precedence?

Question

I\'ve developed an equation parser using a simple stack algorithm that will handle binary (+, -, |, &, *, /, etc) operators, unary (!) operators, and parenthesis.

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Answer 1

It would help if you could describe the grammar you are currently using to parse. Sounds like the problem might lie there!

Edit:

The fact that you don't understand the grammar question and that 'you've written this by hand' very likely explains why you're having problems with expressions of the form '1+11*5' (i.e., with operator precedence). Googling for 'grammar for arithmetic expressions', for example, should yield some good pointers. Such a grammar need not be complicated:

 ::=  +  |
           -  |
          

 ::=  *  |
            /  |
           

 ::= x | y | ... |
             (  ) |
             -  |
             

would do the trick for example, and can be trivially augmented to take care of some more complicated expressions (including functions for example, or powers,...).

I suggest you have a look at this thread, for example.

Almost all introductions to grammars/parsing treat arithmetic expressions as an example.

Note that using a grammar does not at all imply using a specific tool (a la Yacc, Bison,...). Indeed, you most certainly are already using the following grammar:

  ::  |   

   :: + | - | * | /

 ::  | ()

(or something of the kind) without knowing it!