Talk:Parsing/RPN to infix conversion: Difference between revisions

:::::: Thank you! --[[User:Dgamey|Dgamey]] 01:48, 18 December 2011 (UTC)

:: Huh, if you want minimum parentheses and follow the [[wp:Associativity|actual definition]] of associativity, the task itself is incorrect: - and / are non-associative. The term "left-associative" is often loosely used when parsing infix notations, to determine the order of ops in absence of parens, but to do the reverse and requiring minimum number of parens, this kind of definition of associativity is not enough, and you need to know the exact behaviour of the operators (a + b + c requires none, but a - b - c may need one pair, even though both + and - are both loosely "left associative"). The task needs some more work, or there may be other holes after people try to fix the solutions. --[[User:Ledrug|Ledrug]] 17:50, 17 December 2011 (UTC)

::: I didn't write it, I just noticed it was broken. Perhaps it should be knocked back to draft. --[[User:Dgamey|Dgamey]] 18:20, 17 December 2011 (UTC)

:::: By adding the extra example in a table other examples could be added easily. Although for output, perhaps suppressing the detail for all but one case would be appropriate. --[[User:Dgamey|Dgamey]] 18:19, 17 December 2011 (UTC)

:::::::: Yeah, ''that'' was a bug that needed an extra test case. :-) –[[User:Dkf|Donal Fellows]] 09:18, 19 December 2011 (UTC)

: Tcl version is now fixed (it would have helped if the original example had been sensitive to such things, but there you go). –[[User:Dkf|Donal Fellows]] 18:59, 17 December 2011 (UTC)

 

== New Input examples ==

See 'Examples Incorrect' above. An example was added to show that associativity is correctly handled. --[[User:Dgamey|Dgamey]] 16:49, 17 December 2011 (UTC)