From: Robert Klemme <shortcutter@...>
Date: 2008-01-29T17:36:59+09:00
Subject: Re: Logical Operations on Strings

2008/1/28, Michael W. Ryder <_mwryder@worldnet.att.net>:
> Robert Klemme wrote:
> > I believe this implementation is flawed because it returns a string
> > that is too long if self.size > m.size.
>
> Actually I designed it that way so that I could change only part of the
> original string without having to create a mask of 0xFF for the
> remaining characters.

Ah, ok, then this was on purpose.  Personally I'd consider an element
that is not there as 0x00 for OR and AND - that's why I did it this
way.

>  Your implementations look a little cleaner than
> my first try and I will probably use them in the finished version.  I
> still wonder why these weren't implemented in Ruby as I have been using
> them for over 25 years in other languages.

Since Ruby is so flexible chances are that you will find an equally
easy (or easier) way. :-)

> The reason I asked is that sometimes it is easier for me to think in hex
> when creating masks for logical operations.  Plus, I learned the PCL
> codes for printing using hex and it is easier for me to use them that
> way.  In Business Basic to enter a group of hex characters into a string
> I just use A$=$1B2C062C$ to create a 4 character string.  No need to
> enter each character individually.

Then #pack and #unpack are your friends (see Adam's reply).  You could
easily put that in a method if you want a more concise representation,
e.g.

def h(s)
  [s.to_str].pack 'H*'
end

irb(main):005:0> h '212223'
=> "!\"#"
irb(main):006:0> h '414243'
=> "ABC"
irb(main):010:0> h %Q{414243}
=> "ABC"
irb(main):011:0> h %q{414243}
=> "ABC"

Note also, that you can use hex constants in Ruby:

irb(main):001:0> 0x7b
=> 123

but it seems you are more after construction of strings.

Kind regards

robert


-- 
use.inject do |as, often| as.you_can - without end