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comp.lang.ruby

[Helppp xD] Newbie issue

Flaab Mrlinux

11/17/2006 1:57:00 PM

Hi all!!

I've declared a method inside the string class that has to answer the
amount of "X" and "2" chars in a string. The string is ALWAYS gonna be
15 chars size. The code is the following:

class String

# DAME VARIANTES
def variantes
@variantes = 0
15.times do |@cont|
if (self[@cont] == "2" || self[@cont] == "X")
@variantes = @variantes + 1
end
end

return @variantes
end
end

cadena = "XX222XX222XX1X2"
puts cadena.variantes

And the last line ALWAYS ANSWERS a CERO. Why? Why it doesn't enter the
if statement inside the method?

Thx


--
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5 Answers

David Vallner

11/17/2006 2:24:00 PM

0

Flaab Mrlinux wrote:
> Hi all!!
>
> I've declared a method inside the string class that has to answer the
> amount of "X" and "2" chars in a string. The string is ALWAYS gonna be
> 15 chars size. The code is the following:
>
> class String
>
> # DAME VARIANTES
> def variantes
> @variantes = 0
> 15.times do |@cont|
> if (self[@cont] == "2" || self[@cont] == "X")
> @variantes = @variantes + 1
> end
> end
>
> return @variantes
> end
> end
>
> cadena = "XX222XX222XX1X2"
> puts cadena.variantes
>
> And the last line ALWAYS ANSWERS a CERO. Why? Why it doesn't enter the
> if statement inside the method?
>
> Thx
>
>

String#[] returns the integer code of the character at that position.

So, either use

if(self[@cont] == ?2 || self[@cont] == ?X)

or
if(self[@cont..@cont] == "2" || self[@cont..@cont] == "X")

Also:

1. You shouldn't use instance variables when local ones will suffice.
I.e. use "variantes" and "cont" instead of "@variantes" and "@cont"

2. Please send code snippets with identifiers in English - it takes a
little guesswork out of what you're trying to achieve.

3. Smileys and netspeak are fluff and a little out of place for the
medium. Cut out the "xD" and use "Thanks" instead of Thx, please.

David Vallner

Dmitry Buzdin

11/17/2006 2:28:00 PM

0

Check the manual

str[0] will return a numeric representation of the character
what You need is str[0,1] one character starting from the first
position.

Try this:

class String
def variantes
@variantes = 0
Range.new(0, 14).each { |i|
if (self[i,1] == "2" || self[i,1] == "X")
@variantes = @variantes + 1
end
}
return @variantes
end
end

str = "XXXXX22222XXXXX"
puts str.variantes

Dmitry

matthew.moss.coder

11/17/2006 3:00:00 PM

0

Now that you got a couple answers why your comparisons didn't work,
time to suggest a better method.

class String
def variantes
count "2X"
end
end

Flaab Mrlinux

11/17/2006 6:11:00 PM

0

Matthew Moss wrote:
> Now that you got a couple answers why your comparisons didn't work,
> time to suggest a better method.
>
> class String
> def variantes
> count "2X"
> end
> end

Wow THANKS i´m amazed.... =D That's pretty better!

I'm newbie at ruby didn't know it had such a simple way to do this.

Thanks a lot

--
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dblack

11/17/2006 6:30:00 PM

0