This must be a common newbie question, but I can’t find the answer.
Why does string#[] return an ASCII code, rather than a character?
“abc”[1,2] #-> “bc”
“abc”[1…2] #-> “bc”
“abc”[1] #-> 98
On 26.09.2006 15:02, Newbie wrote:
This must be a common newbie question, but I can’t find the answer.
Why does string#[] return an ASCII code, rather than a character?
“abc”[1,2] #-> “bc”
“abc”[1…2] #-> “bc”
“abc”[1] #-> 98
Because there is no character class in Ruby. If you need a one
character string you can do
irb(main):001:0> “abc”[2,1]
=> “c”
irb(main):002:0> “abc”[2].chr
=> “c”
I guess the former is more performant because the internal buffer can be
shared.
Kind regards
robertOn Tue, 26 Sep 2006 22:06:18 +0900
Newbie [email protected] wrote:
This must be a common newbie question, but I can’t find the answer.
Why does string#[] return an ASCII code, rather than a character?
“abc”[1,2] #-> “bc”
“abc”[1…2] #-> “bc”
“abc”[1] #-> 98
It tells you why in “ri String#[]”:
``
Element Reference—If passed a single +Fixnum+, returns the code
of the character at that position. If passed two +Fixnum+ objects,
returns a substring starting at the offset given by the first, and
a length given by the second. If given a range, a substring
containing characters at offsets given by the range is returned.
‘’
– Thomas A.
Why not a 1-character string?
Robert K. wrote:
This must be a common newbie question, but I can’t find the answer.
Why does string#[] return an ASCII code, rather than a character?
“abc”[1,2] #-> “bc”
“abc”[1…2] #-> “bc”
“abc”[1] #-> 98Because there is no character class in Ruby.
That answers what?, which I already knew. I’m asking why?
On Sep 26, 2006, at 11:15 AM, Newbie wrote:
Why not a 1-character string?
Ruby will work this way in the future.
James Edward G. II
Newbie wrote:
Why not a 1-character string?
A one-character string isn’t a character, because a string has the
properties of an array. A character (if there were such a thing in Ruby)
cannot be expanded into two or more characters as a string can.
When you reference a string with a single index, you get back a
character
code, but this is as close to a character or character class as exists
in
Ruby.
Newbie [email protected] writes:
Element Reference—If passed a single +Fixnum+, returns the code
of the character at that position. If passed two +Fixnum+ objects,
returns a substring starting at the offset given by the first, and
a length given by the second. If given a range, a substring
containing characters at offsets given by the range is returned.
‘’
– Thomas A.
That answers what?, which I already knew. I’m asking why?
Probably because a one-character String is 22 bytes and a Fixnum is
4 (on 32-bit archs).
As James said, a future version of Ruby will return a one-character
string in that case. In the meantime if you are just doing
comparisons you can use the Ruby character literal syntax:
next if line[0] == ?#
Steve
On Sep 26, 2006, at 12:15 PM, Newbie wrote:
Why not a 1-character string?
Even if String#[index] returned a 1-character string, you would still
want a way to extract individual code-points/bytes. Right now you have:
s[i..i] # substring starting at position i of length 1
s[i] # code-point at position i
I think in future Ruby versions it is going to be something like:
s[i..i] # substring starting at position i of length 1
s[i] # same as s[i..i]
s.byte(i) # code-point at position i
I’m guessing at String#byte. I know I read something about that but I
couldn’t find a reference right away.
Anyway, as I understand it, the concept of ‘character’ or even
‘position’
is pretty complicated in a fully i18n world (such as with Unicode).
Gary W.
[email protected] wrote:
I think in future Ruby versions it is going to be something like:
In 1.9 it’s #ord:
1.8:
‘a’[0] # => 97
‘a’[0,1] # => a
‘a’[0…0] # => a
1.9:
‘a’[0] # => a
‘a’.ord # => 97
Regards,
Jordan