Re: [FWP] Poor reverse polish calculator

[Ian Phillipps <igp_list2@tesco.net>]

On Sat, 24 Mar 2001 at 10:11:08 -0500, Jeff Pinyan wrote:
> On Mar 24, Jeff Pinyan said:

[a hsiloP calculator]

>   1 while s!(\S+)\s+(\S+)\s*([-+*/])!"$1$3$2"!ee;print

Your 'perl -le' should be 'perl -ne':

perl -ne'1 while s!(\S+)\s+(\S+)\s*([-+*/])!"$1$3$2"!ee;print'

which leads to the following trivial optimisation:

perl -pe'1while s!(\S+)\s+(\S+)\s*([-+*/])!"$1$3$2"!ee'

> 52.
Depends how you count. Mine's 55.

Or, introducing ASCII dependency (and the possibility of syntax errors)
- but you get the [%&,] operators for free:

perl -pe'1while s!(\S+)\s+(\S+)\s*([%-/])!"$1$3$2"!ee'

BTW1:
Using the '.' operator produces some interesting effects when using
perl >= 5.6

BTW2:
Expressions like 'sin(4) 3 +' are entirely legal... a better solution
would allow ' 3 4 sin +' .... [left as an exercise for the reader]

Ian

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