From: jamison edmonds <jamison2000e@...>
Date: 2010-04-11T09:29:35+09:00
Subject: Re: end of sentience has ? y/n, if n please use one "string?"=o.k.

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Thanks to=A0all=A0:)=20
=A0


--- On Thu, 3/25/10, brabuhr@gmail.com <brabuhr@gmail.com> wrote:


From: brabuhr@gmail.com <brabuhr@gmail.com>
Subject: Re: end of sentience has ? y/n, if n please use one "string?"=3Do.=
k.
To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
Date: Thursday, March 25, 2010, 9:27 PM


On Thu, Mar 25, 2010 at 8:32 PM, jamison edmonds <jamison2000e@yahoo.com> w=
rote:
> Still new to programing.
> I'm making a magic 8 ball clone, for fun and to learn by, console based f=
or now. :)
>
> I need a few good examples on how to detect if input has a question mark =
at the end (more than one example/explanation preferably.)
>
> So, I GETS a question in my .rb and if "string?" o.k. else I'd like to sa=
y, need a question with a ? mark at end please.

There are quite a few ways to approach this problem.=A0 If you haven't
already, you can find an overview of various string methods here:
http://www.ruby-doc.org/core/classes/String.html

First let's gets a string:

>> a =3D gets
abcdefg?
=3D> "abcdefg?\n"

I'm assuming you don't care about the newline on the end of gets-ed
string.=A0 So, I'll chomp it first:
http://ruby-doc.org/core/classes/String.html#M000819

>> a.chomp
=3D> "abcdefg?"
>> a
=3D> "abcdefg?\n"
>> a.chomp!
=3D> "abcdefg?"
>> a
=3D> "abcdefg?"

Strings in ruby can in some ways behave like arrays (responding to []):
http://ruby-doc.org/core/classes/String.html#M000771

# substring from last (-1) position to last position (-1)
>> a[-1..-1]
=3D> "?"

# substring of length 1 from last (-1) position
>> a[-1,1]
=3D> "?"

(There is also simply a method like a[-1]:
=A0 >> a[-1]
=A0 =3D> 63
which returns the code for position -1, if you look 63 up in an ASCII
table, you'd see that it corresponds to ?:
=A0 >> 63.chr
=A0 =3D> "?"
but, this behavior is different from ruby 1.8 and ruby 1.9, which is
why I almost didn't mention it here.)

Strings can also be turned into arrays:
http://ruby-doc.org/core/classes/String.html#M000803

>> b =3D a.split('')
=3D> ["a", "b", "c", "d", "e", "f", "g", "?"]
>> b.last
=3D> "?"

And strings can also be matched against patterns:
http://ruby-doc.org/core/classes/String.html#M000778
http://www.regular-expressions.info/ruby.html

# does a have a ! at the end
>> a.match(/\!$/)
=3D> nil
# does a have a ? at the end
>> a.match(/\?$/)
=3D> #<MatchData "?">

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