Hi there!
I’m a ruby newbie, and I’m searching for a way to iterate every char in
a string, but I cannot find any easy way. My problem is to look at every
char in a string and match it with some known letter.
I use the String#each_byte iterator for now, but it still be a poor
solution 
Thanks,
shinya.
On Dec 20, 2005, at 4:52 AM, shinya wrote:
Hi there!
I’m a ruby newbie, and I’m searching for a way to iterate every
char in a string, but I cannot find any easy way. My problem is to
look at every char in a string and match it with some known letter.
I use the String#each_byte iterator for now, but it still be a poor
solution
Thanks,shinya.
The usual idiom is str.split(//).each do |character|
# do stuff with character
end
eg:
logan:/Users/logan% irb
irb(main):001:0> str = “Hello, world!”
=> “Hello, world!”
irb(main):002:0> str.split(//).each do |character|
irb(main):003:1* puts character
irb(main):004:1> end
H
e
l
l
o
,
w
o
r
l
d
!
=> [“H”, “e”, “l”, “l”, “o”, “,”, " ", “w”, “o”, “r”, “l”, “d”, “!”]
if the extraneous typing bothers you, you can always add it to String.
class String
def each_char(&block)
split(//).each(&block)
self
end
end
Logan C. wrote:
The usual idiom is str.split(//).each do |character|
# do stuff with character
end
Thank you very much! I did it 
bye!
shinya.
“hello world”.each_byte{|i| puts “%c” % i}
On 12/20/05, Logan C. [email protected] wrote:
shinya.
The usual idiom is str.split(//).each do |character|
# do stuff with character
end
String#scan with a block is lighter weight, and less wordy:
str.scan(/./) do |character|
end
Logan C. wrote:
“r”
“l”
“d”Where’d my newlines go?
Heh, good point. Thanks for mentioning this. I think this might be quite
a common pit fall.
Time to grep my code and see if this could possibly cause trouble
anywhere…
On Dec 20, 2005, at 6:21 AM, Mark H. wrote:
Thanks,
stuff
end
str = “Hello\nWorld”
str.scan(/./) do |character|
p character
end
irb(main):015:0> str.scan(/./) do |character|
irb(main):016:1* p character
irb(main):017:1> end
“H”
“e”
“l”
“l”
“o”
“W”
“o”
“r”
“l”
“d”
Where’d my newlines go? 
irb(main):021:0> str.split(//).each do |character|
irb(main):022:1* p character
irb(main):023:1> end
“H”
“e”
“l”
“l”
“o”
“\n”
“W”
“o”
“r”
“l”
“d”
If you want to use scan, you should use scan(/./m)
irb(main):024:0> str.scan(/./m) do |character|
irb(main):025:1* p character
irb(main):026:1> end
“H”
“e”
“l”
“l”
“o”
“\n”
“W”
“o”
“r”
“l”
“d”
i’ve always used this:
0.upto(string.length-1) do |n|
p string[n,1]
end
anything wrong with this?
greetings, Dirk.
2005/12/20, Florian GroÃ? [email protected]:
“Wrong” is a strong word, but I’d say this isn’t ideal Ruby for two
reasons:
| QuickBench Session Started |
| 300 Iterations |
|---|
user system total real
The string s above was 4000 x characters.
I was quite surprised the scan was so much slower, especially compared
to split, which creates an array every time.
Ryan
shinya wrote:
Hi there!
I’m a ruby newbie, and I’m searching for a way to iterate every char in
a string, but I cannot find any easy way. My problem is to look at every
char in a string and match it with some known letter.
If you just want to know if a string contains a character:
puts "Yep!" if str.include?("X")
I use the String#each_byte iterator for now, but it still be a poor
solution
Others have suggested various iterators, but why not use standard jcode
lib?
require 'jcode'
str.each_char { |c| puts c }On Dec 20, 2005, at 3:35 PM, Dirk M. wrote:
i’ve always used this:
0.upto(string.length-1) do |n|
p string[n,1]
endanything wrong with this?
You mean besides the fact that it’s not very Rubyish?
Seriously, it seems fine, though I prefer each_byte() or scan(/./m).
James Edward G. II
On 12/20/05, Bob S. [email protected] wrote:
Others have suggested various iterators, but why not use standard jcode lib?
require 'jcode' str.each_char { |c| puts c }
In case anyone is curious, the above just uses scan(/./m), and is even
slower in my benchmark because of the extra method calls. But in
reality all are quite fast enough, and the performance differences
aren’t all that significant.
Ryan
a=“123”
0.upto(a.length) { |i| puts a[i…i] }
| QuickBench Session Started |
300 Iterations user system total real
- s.each_byte{|b| b.chr … 2.656000 0.000000 2.656000 (
2.669000)
each_char should beat the current leader as b.chr is not needed.
Strange it is not a part of Ruby as the char is the most natural part of
a string.
Christer
a.split( // ).each { |c| puts c }
j.
On 12/20/05, Lyndon S. [email protected] wrote:
char in a string and match it with some known letter.
Into RFID? www.rfidnewsupdate.com Simple, fast, news.
–
“Remember. Understand. Believe. Yield! → http://ruby-lang.org”
Jeff W.
On Dec 20, 2005, at 6:32 PM, Christer N. wrote:
Strange it is not a part of Ruby as the char is the most natural
part of
a string.
I don’t think that is true. The semantics of each_byte are quite clear
but exactly what is a character? In some encodings
one byte is the same as one character but in other encodings it might
be two bytes or in others in might be a variable number of bytes.
Iterating by ‘character’ only has meaning with respect to a character
set
encoding and a Ruby string generally doesn’t have that sort of
information.
I think it is has been said before but, a Ruby string is more like an
array of bytes than a sequence of code points in an (implicit)
character set.
Gary W.
Robert K. wrote:
Many roads to Rome…
robert
or even
a.scan(/./) { |c| p c }
Kev
Kev J. wrote:
a.length.times {|i| puts a[i].chr}
Many roads to Rome…
robertor even
a.scan(/./) { |c| p c }
We had that already: your version ignores newlines.
robertLyndon S. wrote:
a=“123”
0.upto(a.length) { |i| puts a[i…i] }
Alternatively:
a.length.times {|i| puts a[i].chr}
Many roads to Rome…
robertKev J. wrote:
a = “ook\nook\tEeek!\n”
a.scan(/.|\s/) { |c| p c }
a.scan(/./m) {|c| p c } # m is for multi-line
Cheers,
Dave
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