Re^2: a timid approach to parsing arithmetic expressions in perl

Hi ikegami and thank you very much for the interest in this,

Using minor modifictions I've implemented also POW for this evaluator
I've also added as a test the expression "3**(6-1*4)**2" which should eval to 81.
About the warnings , the compiler already evaluated the expression to -6 and the bug
was caused by the fact that negative numbers were not yet recognised.
Now both of these are fixed.

Comment on Re^2: a timid approach to parsing arithmetic expressions in perl

Replies are listed 'Best First'.
Re^3: a timid approach to parsing arithmetic expressions in perl by ikegami (Patriarch) on Jul 27, 2008 at 07:57 UTC
`3*(6-14)2` is a bad test since `(32)2` happens to equal `3(22)` When I use the `342` I had previously mentioned, your code returns `6561` (`(34)2`) instead of `43046721` (`3(42)`). `>perl -le"print 34**2" 43046721` [download]	[reply] [d/l] [select]
Re^3: a timid approach to parsing arithmetic expressions in perl by spx2 (Deacon) on Jul 26, 2008 at 16:02 UTC
hmm,seems that the right associative operator must be parsed in a different way... the problem about evaluating "342" still persists ... however if paranthesis are employed and we re-write like this "3(42)" it will be evaluated correctly. uhm,the only way I can see this as beeing done is by using a stack and putting all 3,4,2 on it if the operator ** is found and afterwards start emptying the stack by taking two of them,evaling putting them back and so on.	[reply]