thr3ads.net - Rails - Get the first character from a string? [Jul 2008]

If this information is useful, please help other people find it:
Share via:

KathysKode-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2008-Jul-13 13:01 UTC

Get the first character from a string?

I''ve got a math function where I''m converting a base36 number
to a
base 10 integer and it works wonderfully, except when the first
character is a zero.
I could get this method to work if I could look at the first position
in a string, and if it was a zero, I''d then add a zero to the first
position of the resulting string.
Here''s the equation (and its compliment);

  def calc_ovalue(barcode)
    barcode.to_i(36)
  end

  def calc_other(barcode)
    onum = calc_ovalue(barcode)
    if onum.odd?
      (onum + 1).to_s(36).upcase
    else
      (onum - 1).to_s(36).upcase
    end
  end

some examples of accepeting the first value and calculating the second
two are;
0N5F  0N5G  ovalue = 30003
0V9B  0V9C  ovalue = 40511
6JYV  6JYW ovalue = 305815

Thank you,
Kathleen
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

Thorsten Müller

2008-Jul-13 13:50 UTC

head link

Re: Get the first character from a string?

if you have a string @str, then
@str[0] will give you the charactercode of the first char
that''s already enough to test against the charcode of a zero which is
48

if yo prefer to work with a string as result, use
@str[0,1]
this gives a string result (0 = from position, 1 = length)
or
@str[0..0]
returns a string too, the range is startposition to endposition
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

Matt Williams

2008-Jul-13 14:32 UTC

head link

Re: Get the first character from a string?

Assuming that s is the string; s[0] is the first character.  s[0].chr
="1" or s[0]==48 (see the irb session below)>> a="1234"
=> "1234">> b="01234"
=> "01234">> a[0]
=> 49>> a[0].chr
=> "1">> b[0]
=> 48>> b[0].chr
=> "0">> 
Hope that helps,
Matt


On Sun, 2008-07-13 at 06:01 -0700,
KathysKode-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
wrote:> I''ve got a math function where I''m converting a base36
number to a
> base 10 integer and it works wonderfully, except when the first
> character is a zero.
> I could get this method to work if I could look at the first position
> in a string, and if it was a zero, I''d then add a zero to the
first
> position of the resulting string.
> Here''s the equation (and its compliment);
> 
>   def calc_ovalue(barcode)
>     barcode.to_i(36)
>   end
> 
>   def calc_other(barcode)
>     onum = calc_ovalue(barcode)
>     if onum.odd?
>       (onum + 1).to_s(36).upcase
>     else
>       (onum - 1).to_s(36).upcase
>     end
>   end
> 
> some examples of accepeting the first value and calculating the second
> two are;
> 0N5F  0N5G  ovalue = 30003
> 0V9B  0V9C  ovalue = 40511
> 6JYV  6JYW ovalue = 305815
> 
> Thank you,
> Kathleen
> > 

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

KathysKode-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2008-Jul-13 18:06 UTC

head link

Re: Get the first character from a string?

Matt,
I''m seeing how to test the first character of the incoming string
which is (barcode) (see function)
  def calc_other(barcode)
    onum = calc_ovalue(barcode)
    if onum.odd?
      (onum + 1).to_s(36).upcase
    else
      (onum - 1).to_s(36).upcase
    end
    if barcode[0] == 48
      "0" + return
    end
  end

But then, I don''t see how to attach the preceding zero if the incoming
(barcode) has one. I know this looks stupid, but what I''m attempting
is to add a zero to the first position of the result. I assume result
= string?
Thank you,
Kathleen

On Jul 13, 8:32 am, Matt Williams
<m...-djWhm22DhGpWk0Htik3J/w@public.gmane.org>
wrote:> Assuming that s is the string; s[0] is the first character.  s[0].chr =>
"1" or s[0]==48 (see the irb session below)
>
> >> a="1234"
> => "1234"
> >> b="01234"
> => "01234"
> >> a[0]
> => 49
> >> a[0].chr
> => "1"
> >> b[0]
> => 48
> >> b[0].chr
> => "0"
>
> Hope that helps,
> Matt
>
> On Sun, 2008-07-13 at 06:01 -0700,
KathysK...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org wrote:
> > I''ve got a math function where I''m converting a
base36 number to a
> > base 10 integer and it works wonderfully, except when the first
> > character is a zero.
> > I could get this method to work if I could look at the first position
> > in a string, and if it was a zero, I''d then add a zero to the
first
> > position of the resulting string.
> > Here''s the equation (and its compliment);
>
> >   def calc_ovalue(barcode)
> >     barcode.to_i(36)
> >   end
>
> >   def calc_other(barcode)
> >     onum = calc_ovalue(barcode)
> >     if onum.odd?
> >       (onum + 1).to_s(36).upcase
> >     else
> >       (onum - 1).to_s(36).upcase
> >     end
> >   end
>
> > some examples of accepeting the first value and calculating the second
> > two are;
> > 0N5F  0N5G  ovalue = 30003
> > 0V9B  0V9C  ovalue = 40511
> > 6JYV  6JYW ovalue = 305815
>
> > Thank you,
> > Kathleen--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

Marlon Moyer

2008-Jul-13 19:20 UTC

head link

Re: Get the first character from a string?

will the result always be 4 chars?  If so, could you do something like

return_val = my_val.rjust(4).gsub(" ","0")


On Sun, Jul 13, 2008 at 1:06 PM, KathysKode@gmail.com
<KathysKode@gmail.com>
wrote:
>
> Matt,
> I'm seeing how to test the first character of the incoming string
> which is (barcode) (see function)
>   def calc_other(barcode)
>    onum = calc_ovalue(barcode)
>    if onum.odd?
>      (onum + 1).to_s(36).upcase
>    else
>      (onum - 1).to_s(36).upcase
>    end
>     if barcode[0] == 48
>      "0" + return
>    end
>  end
>
> But then, I don't see how to attach the preceding zero if the incoming
> (barcode) has one. I know this looks stupid, but what I'm attempting
> is to add a zero to the first position of the result. I assume result
> = string?
> Thank you,
> Kathleen
>
> On Jul 13, 8:32 am, Matt Williams <m...@harpstar.com> wrote:
> > Assuming that s is the string; s[0] is the first character.  s[0].chr
=> > "1" or s[0]==48 (see the irb session below)
> >
> > >> a="1234"
> > => "1234"
> > >> b="01234"
> > => "01234"
> > >> a[0]
> > => 49
> > >> a[0].chr
> > => "1"
> > >> b[0]
> > => 48
> > >> b[0].chr
> > => "0"
> >
> > Hope that helps,
> > Matt
> >
> > On Sun, 2008-07-13 at 06:01 -0700, KathysK...@gmail.com wrote:
> > > I've got a math function where I'm converting a base36
number to a
> > > base 10 integer and it works wonderfully, except when the first
> > > character is a zero.
> > > I could get this method to work if I could look at the first
position
> > > in a string, and if it was a zero, I'd then add a zero to the
first
> > > position of the resulting string.
> > > Here's the equation (and its compliment);
> >
> > >   def calc_ovalue(barcode)
> > >     barcode.to_i(36)
> > >   end
> >
> > >   def calc_other(barcode)
> > >     onum = calc_ovalue(barcode)
> > >     if onum.odd?
> > >       (onum + 1).to_s(36).upcase
> > >     else
> > >       (onum - 1).to_s(36).upcase
> > >     end
> > >   end
> >
> > > some examples of accepeting the first value and calculating the
second
> > > two are;
> > > 0N5F  0N5G  ovalue = 30003
> > > 0V9B  0V9C  ovalue = 40511
> > > 6JYV  6JYW ovalue = 305815
> >
> > > Thank you,
> > > Kathleen
> >
>
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to rubyonrails-talk@googlegroups.com
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

KathysKode-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2008-Jul-13 20:22 UTC

head link

Re: Get the first character from a string?

Marlon,
Yes. The problem is that if I submit a barcode like 0123 the other
barcode is calculated as 124. If there is a character other than zero
in the first position it works just fine.
Where are you suggesting that I put the return_val line of code you
show?
Is that gsub example putting a zero at the end of the string?
What / How would you amend the return value of the calc_other
function. Isn''t the result of any method the value inside the
''return''
keyword?
If so, why can''t the ''return'' value be modified
before the function
closes?
I seem to be having a problem ''seeing the forest through the
trees''.
Kathleen

On Jul 13, 1:20 pm, "Marlon Moyer"
<marlon.mo...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> will the result always be 4 chars?  If so, could you do something like
>
> return_val = my_val.rjust(4).gsub(" ","0")
>
> On Sun, Jul 13, 2008 at 1:06 PM,
KathysK...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<KathysK...-Re5JQEeQqe8@public.gmane.orgm>
> wrote:
>
>
>
> > Matt,
> > I''m seeing how to test the first character of the incoming
string
> > which is (barcode) (see function)
> >   def calc_other(barcode)
> >    onum = calc_ovalue(barcode)
> >    if onum.odd?
> >      (onum + 1).to_s(36).upcase
> >    else
> >      (onum - 1).to_s(36).upcase
> >    end
> >     if barcode[0] == 48
> >      "0" + return
> >    end
> >  end
>
> > But then, I don''t see how to attach the preceding zero if the
incoming
> > (barcode) has one. I know this looks stupid, but what I''m
attempting
> > is to add a zero to the first position of the result. I assume result
> > = string?
> > Thank you,
> > Kathleen
>
> > On Jul 13, 8:32 am, Matt Williams
<m...-djWhm22DhGpWk0Htik3J/w@public.gmane.org> wrote:
> > > Assuming that s is the string; s[0] is the first character.
 s[0].chr => > > "1" or s[0]==48 (see the irb session below)
>
> > > >> a="1234"
> > > => "1234"
> > > >> b="01234"
> > > => "01234"
> > > >> a[0]
> > > => 49
> > > >> a[0].chr
> > > => "1"
> > > >> b[0]
> > > => 48
> > > >> b[0].chr
> > > => "0"
>
> > > Hope that helps,
> > > Matt
>
> > > On Sun, 2008-07-13 at 06:01 -0700,
KathysK...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org wrote:
> > > > I''ve got a math function where I''m
converting a base36 number to a
> > > > base 10 integer and it works wonderfully, except when the
first
> > > > character is a zero.
> > > > I could get this method to work if I could look at the first
position
> > > > in a string, and if it was a zero, I''d then add a
zero to the first
> > > > position of the resulting string.
> > > > Here''s the equation (and its compliment);
>
> > > >   def calc_ovalue(barcode)
> > > >     barcode.to_i(36)
> > > >   end
>
> > > >   def calc_other(barcode)
> > > >     onum = calc_ovalue(barcode)
> > > >     if onum.odd?
> > > >       (onum + 1).to_s(36).upcase
> > > >     else
> > > >       (onum - 1).to_s(36).upcase
> > > >     end
> > > >   end
>
> > > > some examples of accepeting the first value and calculating
the second
> > > > two are;
> > > > 0N5F  0N5G  ovalue = 30003
> > > > 0V9B  0V9C  ovalue = 40511
> > > > 6JYV  6JYW ovalue = 305815
>
> > > > Thank you,
> > > > Kathleen--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

Marlon Moyer

2008-Jul-13 21:02 UTC

head link

Re: Get the first character from a string?

This is how it could be done:

def calc_ovalue(barcode)
  barcode.to_i(36)
end

def calc_other(barcode)
  onum = calc_ovalue(barcode)
  if onum % 2 == 1
    onum+=1
  else
    onum-=1
  end
  onum.to_s(36).rjust(4).gsub(" ","0").upcase
end




On Sun, Jul 13, 2008 at 3:22 PM, KathysKode@gmail.com
<KathysKode@gmail.com>
wrote:
>
> Marlon,
> Yes. The problem is that if I submit a barcode like 0123 the other
> barcode is calculated as 124. If there is a character other than zero
> in the first position it works just fine.
> Where are you suggesting that I put the return_val line of code you
> show?
> Is that gsub example putting a zero at the end of the string?
> What / How would you amend the return value of the calc_other
> function. Isn't the result of any method the value inside the
'return'
> keyword?
> If so, why can't the 'return' value be modified before the
function
> closes?
> I seem to be having a problem 'seeing the forest through the
trees'.
> Kathleen
>
> On Jul 13, 1:20 pm, "Marlon Moyer" <marlon.mo...@gmail.com>
wrote:
> > will the result always be 4 chars?  If so, could you do something like
> >
> > return_val = my_val.rjust(4).gsub(" ","0")
> >
> > On Sun, Jul 13, 2008 at 1:06 PM, KathysK...@gmail.com <
> KathysK...@gmail.com>
> > wrote:
> >
> >
> >
> > > Matt,
> > > I'm seeing how to test the first character of the incoming
string
> > > which is (barcode) (see function)
> > >   def calc_other(barcode)
> > >    onum = calc_ovalue(barcode)
> > >    if onum.odd?
> > >      (onum + 1).to_s(36).upcase
> > >    else
> > >      (onum - 1).to_s(36).upcase
> > >    end
> > >     if barcode[0] == 48
> > >      "0" + return
> > >    end
> > >  end
> >
> > > But then, I don't see how to attach the preceding zero if the
incoming
> > > (barcode) has one. I know this looks stupid, but what I'm
attempting
> > > is to add a zero to the first position of the result. I assume
result
> > > = string?
> > > Thank you,
> > > Kathleen
> >
> > > On Jul 13, 8:32 am, Matt Williams <m...@harpstar.com>
wrote:
> > > > Assuming that s is the string; s[0] is the first character. 
s[0].chr
> => > > > "1" or s[0]==48 (see the irb session below)
> >
> > > > >> a="1234"
> > > > => "1234"
> > > > >> b="01234"
> > > > => "01234"
> > > > >> a[0]
> > > > => 49
> > > > >> a[0].chr
> > > > => "1"
> > > > >> b[0]
> > > > => 48
> > > > >> b[0].chr
> > > > => "0"
> >
> > > > Hope that helps,
> > > > Matt
> >
> > > > On Sun, 2008-07-13 at 06:01 -0700, KathysK...@gmail.com
wrote:
> > > > > I've got a math function where I'm converting a
base36 number to a
> > > > > base 10 integer and it works wonderfully, except when
the first
> > > > > character is a zero.
> > > > > I could get this method to work if I could look at the
first
> position
> > > > > in a string, and if it was a zero, I'd then add a
zero to the first
> > > > > position of the resulting string.
> > > > > Here's the equation (and its compliment);
> >
> > > > >   def calc_ovalue(barcode)
> > > > >     barcode.to_i(36)
> > > > >   end
> >
> > > > >   def calc_other(barcode)
> > > > >     onum = calc_ovalue(barcode)
> > > > >     if onum.odd?
> > > > >       (onum + 1).to_s(36).upcase
> > > > >     else
> > > > >       (onum - 1).to_s(36).upcase
> > > > >     end
> > > > >   end
> >
> > > > > some examples of accepeting the first value and
calculating the
> second
> > > > > two are;
> > > > > 0N5F  0N5G  ovalue = 30003
> > > > > 0V9B  0V9C  ovalue = 40511
> > > > > 6JYV  6JYW ovalue = 305815
> >
> > > > > Thank you,
> > > > > Kathleen
> >
>
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to rubyonrails-talk@googlegroups.com
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

Michael Graff

2008-Jul-14 00:56 UTC

head link

Re: Get the first character from a string?

How about this?  All operations here should be (fairly) cheap.

def next_barcode(barcode)
  length = barcode.length

  val = barcode.to_i(36)
  if val.odd?
    val += 1
  else
    val -= 1
  end

  ret = val.to_s(36).upcase
  (''0'' * (length - ret.length)) + ret
end

tests = [ ''AAAAAA'', ''AAAAAZ'',
''012345'', ''00000Z'',
''00ZZZZ'' ]

tests.each do |test|
  puts "#{test} --> #{next_barcode(test)}"
end

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

Rails - Jul 2008 - Get the first character from a string?

Get the first character from a string?

Re: Get the first character from a string?

Re: Get the first character from a string?

Re: Get the first character from a string?

Re: Get the first character from a string?

Re: Get the first character from a string?

Re: Get the first character from a string?

Re: Get the first character from a string?