From: Assaph Mehr <assaph@...>
Date: 2005-05-19T09:05:13+09:00
Subject: Re: accessing each character of a string


Boris Glawe wrote:
> Hi,
>
> my problem is obviously very basic, but how to I acces for example
the third
> character of the string "hello" ??
>
> The [] method does not behave as expected, the each method returns
the whole
> string, the methods of Enumerable mixin don't help me...
>
> This can't be that hard to solve!?
>
> thanks Boris

Just convert the Fixnum into a character:

irb(main):005:0> s = 'hello'
=> "hello"
irb(main):006:0> s[2]
=> 108
irb(main):007:0> s[2].chr
=> "l"

>From the docs:

--------------------------------------------------------------
String#[]
     str[fixnum]                 => fixnum or nil
     str[fixnum, fixnum]         => new_str or nil
     str[range]                  => new_str or nil
     str[regexp]                 => new_str or nil
     str[regexp, fixnum]         => new_str or nil
     str[other_str]              => new_str or nil
     str.slice(fixnum)           => fixnum or nil
     str.slice(fixnum, fixnum)   => new_str or nil
     str.slice(range)            => new_str or nil
     str.slice(regexp)           => new_str or nil
     str.slice(regexp, fixnum)   => new_str or nil
     str.slice(other_str)        => new_str or nil
------------------------------------------------------------------------
     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.
In
     all three cases, if an offset is negative, it is counted from the
     end of _str_. Returns +nil+ if the initial offset falls outside
the
     string, the length is negative, or the beginning of the range is
     greater than the end.

     If a +Regexp+ is supplied, the matching portion of _str_ is
     returned. If a numeric parameter follows the regular expression,
     that component of the +MatchData+ is returned instead. If a
     +String+ is given, that string is returned if it occurs in _str_.
     In both cases, +nil+ is returned if there is no match.

        a = "hello there"
        a[1]                   #=> 101
        a[1,3]                 #=> "ell"
        a[1..3]                #=> "ell"
        a[-3,2]                #=> "er"
        a[-4..-2]              #=> "her"
        a[12..-1]              #=> nil
        a[-2..-4]              #=> ""
        a[/[aeiou](.)\1/]      #=> "ell"
        a[/[aeiou](.)\1/, 0]   #=> "ell"
        a[/[aeiou](.)\1/, 1]   #=> "l"
        a[/[aeiou](.)\1/, 2]   #=> nil
        a["lo"]                #=> "lo"
        a["bye"]               #=> nil