From: Ruby Newbee <rubynewbee@...>
Date: 2009-11-25T09:24:31+09:00
Subject: Re: can't understand for String.delete

ah~ thanks, I got it.
never saw this syntax in my other languages of programming, :-)

2009/11/24 Jesús Gabriel y Galán <jgabrielygalan@gmail.com>:
> On Tue, Nov 24, 2009 at 2:41 PM, Ruby Newbee <rubynewbee@gmail.com> wrote:
>>     Returns a copy of _str_ with all characters in the intersection of
>>     its arguments deleted. Uses the same rules for building the set of
>>     characters as +String#count+.
>>
>>        "hello".delete "l","lo"        #=> "heo"
>>        "hello".delete "lo"            #=> "he"
>>        "hello".delete "aeiou", "^e"   #=> "hell"
>>        "hello".delete "ej-m"          #=> "ho"
>>
>>
>> What does this mean?
>> I can't understand for the rules.
>
> What it means is that it builds a character set performing the
> intersection of all arguments to the method. So if you do
> s.delete("h", "he") the intersection of the arguments is "h", because
> it's the only one present in all arguments. If the arguments don't
> intersect nothing is deleted:
>
> irb(main):001:0> "hello".delete "h", "e"
> => "hello"
>
> The other part of the explanation means that as the documentation for
> String#count says
> (http://ruby-doc.org/core/classes/String.html#M000834):
>
> "Any other_str that starts with a caret (^) is negated. The sequence
> c1—c2 means all characters between c1 and c2. "
>
> This means that s.delete("^aeiou") will remove all consonants and
> leave the vocals, and that s.delete("a-m") will delete all characters
> between "a" and "m":
>
> irb(main):002:0> "hello".delete "a-m"
> => "o"
> irb(main):003:0> "hello".delete "^aeiou"
> => "eo"
> irb(main):004:0>
>
> Hope this helps,
>
> Jesus.
>
>