From: Christian <chippersbox@...>
Date: 2008-03-17T10:32:59+09:00
Subject: Re: Cipher

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input = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
!@#$%^&*()_+-={}|[]\;\':",./<>?`~'
input.tr! "A-Za-z", "N-ZA-Mn-za-m"
=> "nopqrstuvwxyzabcdefghijklmNOPQRSTUVWXYZABCDEFGHIJKLM
!@\#$%^&*()_+-={}|[]\\;':\",./<>?`~"

On Mon, Mar 17, 2008 at 11:16 AM, Thomas Wieczorek <wieczo.yo@googlemail.com>
wrote:

> On Mon, Mar 17, 2008 at 1:50 AM, Max Zhou <ball908765@yahoo.com> wrote:
> > I am trying to make a program that takes what you input, and encrypts it
> by turning a to p, b to q, z to b, etc.  It moves the letter 2 spaces to the
> left (a to c) and moves it down (c to p).  (See below.)  Even though you can
> just say that a will be n, how do you seperate each letter and turn it into
> a string?  Please put it in terms that a Ruby beginner would understand.
> >   abcdefghijklm
> >   nopqrstuvwxyz
> >
>
> You can split a string with the String#split method:
> irb
> > "Foobar".split(//)
> => ["F", "o", "o", "b", "a", "r"]
>
> You can get the ASCII value of a character either with ?character:
> > ?F
> => 70
>
> If you want to loop the splitted string, try eval(has anyone a better
> solution?):
> > "Foobar".split(//).each { |c| puts eval("?#{c}") }
>
> You can use Fixnum#chr to turn an ASCII value in a character:
> > 65.chr #=> "A"
>
> You're trying to implement the ROT13 or ROTx algorithm. A naive
> approach, still buggy might look like that:
> plaintext = "Hello"
> encrypted = ""
> plaintext.split(//).each { |c| i=eval("?#{c}"); encrypted << (i+13).chr }
> puts encrypted #=> Uryy|
>
> As you see, the encrypted string contains a |(vertical line) and it
> also chokes on spaces. I leave the rest to you. Ask again if you're
> stuck.
>
> Regards, Thomas
>
>


-- 

"Every child has many wishes. Some include a wallet, two chicks and a cigar,
but that's another story."

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