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comp.lang.ruby

newbie question re: variable assignment

Simon.Mullis

4/13/2005 5:41:00 PM

Hello All,

I am curious as to the general concensus and reaction to me asking a
question that is most probably almost embarrassing in it's stupidity.

Shall we find out?

Let's say I wanted to convert a bunch of numbers to their ascii values.

Why doesn't this work?

1.upto(9) do |x|
puts ?#{x}
end

I am in my first few hours of Rubydom so please - pity. Not ridicule!
;-)

Thanks in advance...

SM

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6 Answers

Patrick Hurley

4/13/2005 6:00:00 PM

0

On 4/13/05, Simon.Mullis@equinoxsolutions.com
<Simon.Mullis@equinoxsolutions.com> wrote:
> Shall we find out?

We want to be the friendly news group, so starting out questions are welcome :-)

> Why doesn't this work?
>
> 1.upto(9) do |x|
> puts ?#{x}
> end

The #{ } escape is for with quoted strings. You could do something
similar to what you write using and eval; however, I think you would
be better off with:

65.upto(75) { |x| puts x.chr }

Patrick

Peter C. Verhage

4/13/2005 6:03:00 PM

0

Simon.Mullis@equinoxsolutions.com wrote:
> Why doesn't this work?
>
> 1.upto(9) do |x|
> puts ?#{x}
> end

This doesn't work because "puts ?#{x}" isn't a valid statement. If you
change this line to "puts x.chr" it should work. I don't know what you
wanted to do with the "?#{x}", so I can't really comment on that... :/

Regards,

Peter

Trans

4/13/2005 6:13:00 PM

0

Hi--
Dont; worry this is a low bite board :-)

> Why doesn't this work?
>
> 1.upto(9) do |x|
> puts ?#{x}
> end

Well, its cuz you're trying to do string interpolation directly into
ruby code, which can't be done. The interpolation (i.e. #{x}) only
works in strings. Secondly, the ? is a literal form and not a method,
so you can;t pass it arguments. To get the ascii value of a string use
str[n] where n is the index of the character you wish to convert, in
this case 0.

1.upto(9) do |x|
puts "#{x}"[0]
end

BTW, I believe this will change in future verions of Ruby since Ruby
will be gaining more advanced encoding. So instead there will be a
specific method, like String#ascii(n), or something, to do this.
[Correct me if I am misinformed all.] But for now the above is the way.

T.

Robert Klemme

4/13/2005 6:19:00 PM

0


"Trans" <transfire@gmail.com> schrieb im Newsbeitrag
news:1113415954.205046.176340@z14g2000cwz.googlegroups.com...
> Hi--
> Dont; worry this is a low bite board :-)
>
>> Why doesn't this work?
>>
>> 1.upto(9) do |x|
>> puts ?#{x}
>> end
>
> Well, its cuz you're trying to do string interpolation directly into
> ruby code, which can't be done. The interpolation (i.e. #{x}) only
> works in strings. Secondly, the ? is a literal form and not a method,
> so you can;t pass it arguments. To get the ascii value of a string use
> str[n] where n is the index of the character you wish to convert, in
> this case 0.
>
> 1.upto(9) do |x|
> puts "#{x}"[0]
> end

or

1.upto(9) do |x|
puts x.to_s[0]
end

or (with some knowledge of ASCII characterset)

1.upto(9) do |x|
puts ?0 + x
end

> BTW, I believe this will change in future verions of Ruby since Ruby
> will be gaining more advanced encoding. So instead there will be a
> specific method, like String#ascii(n), or something, to do this.
> [Correct me if I am misinformed all.] But for now the above is the way.

Yeah probably. But for the time being your solution works.

Kind regards

robert

Douglas Livingstone

4/13/2005 6:27:00 PM

0

> 1.upto(9) do |x|
> puts "#{x}"[0]
> end
>

You can also use .to_s (convert to string) directly:

1.upto(9) { |x| puts x.to_s[0] }

Douglas

Douglas Livingstone

4/13/2005 6:30:00 PM

0

On 4/13/05, Douglas Livingstone <rampant@gmail.com> wrote:
> > 1.upto(9) do |x|
> > puts "#{x}"[0]
> > end
> >
>
> You can also use .to_s (convert to string) directly:
>
> 1.upto(9) { |x| puts x.to_s[0] }
>

Or even:

puts (1..9).collect {|x| x.to_s[0] }

Just started playing with #collect yesterday, I like it :)

Douglas