# What is '?' in Ruby? **URL:** \ **Category:** Ruby\ **Created:** [March 1, 2010, 1:30pm UTC](https://www.ruby-forum.com/t/what-is-in-ruby/184361 "2010-03-01T13:30:58Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![ghostrifle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f04885/32.png) [@ghostrifle](https://www.ruby-forum.com/u/ghostrifle)\ **Post date:** [March 1, 2010, 1:30pm UTC](https://www.ruby-forum.com/t/what-is-in-ruby/184361/1 "2010-03-01T13:30:58Z")
Hello! To clarify the question I need to say some more. I know Ruby 1.8 ‘?a’ =\> 97 Ruby 1.9 ‘?a’ =\> “a” Really I would like to where I can get specification of operator, keyword, function or something else I do know what is name of ‘?’… I have surfed [ruby-lang.org](http://ruby-lang.org) and [ruby-doc.org](http://ruby-doc.org) but can’t find information about it. Is it an unofficial something? Just a bit here [http://www.ruby-doc.org/docs/ProgrammingRuby/](http://www.ruby-doc.org/docs/ProgrammingRuby/), “Standard Types” chapter: ?a # character code But it is related to 1.8 version, not for 1.9. Please just point to chapter of ruby specification where I can find anything about ‘?’ if it is. And are there methods which helps to know what is ‘?’? Thank you in advance. ---
**Author:** ![ghostrifle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f04885/32.png) [@ghostrifle](https://www.ruby-forum.com/u/ghostrifle)\ **Post date:** [March 1, 2010, 3:15pm UTC](https://www.ruby-forum.com/t/what-is-in-ruby/184361/2 "2010-03-01T15:15:11Z")
Alexander Bubnov wrote: > I know > Ruby 1.8 ‘?a’ =\> 97 > Ruby 1.9 ‘?a’ =\> “a” It’s a character literal - but in 1.9 a character is a one-character string (possibly multiple bytes) rather than an Integer for a single byte in 1.8. You’ll see the same difference with “a”[0] > Really I would like to where I can get specification of operator, > keyword, function or something else I do know what is name of ‘?’… For 1.8 (actually 1.6.8 🙂 [http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut\_stdtypes.html](http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_stdtypes.html) “You can also get the integer value corresponding to an ASCII character or escape sequence by preceding it with a question mark” For 1.9: you have to buy the more recent version of this book. > Please just point to chapter of ruby specification Please point me to any ruby specification 🙂 Actually, there is a project which is attempting to create a specification of Ruby for standardisation; it was linked to in this mailing list within the last few days. However it’s using 1.8.7 as it’s starting point, on the grounds that 1.9 is still a moving target. I attempted to document strings in 1.9, but only got as far as documenting about 200 behaviours. > ---
**Author:** ![ghostrifle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f04885/32.png) [@ghostrifle](https://www.ruby-forum.com/u/ghostrifle)\ **Post date:** [March 1, 2010, 3:22pm UTC](https://www.ruby-forum.com/t/what-is-in-ruby/184361/3 "2010-03-01T15:22:22Z")
On Mar 1, 2010, at 1:31 PM, Alexander Bubnov wrote: > Types" chapter: > ?a # character code > > But it is related to 1.8 version, not for 1.9. > Please just point to chapter of ruby specification where I can find > anything about ‘?’ if it is. And are there methods which helps to know > what is ‘?’? Ruby 1.8 sees strings as a sequence of bytes. So “a”[0] #=\> 97 yields 97 (because 97 is the value representing the character a in an ASCII-String). If you want to compare this to some character, you need the character code of “a” (because no one wants to have an ASCII-Table next to them when programming). ?a gives you the character code of a. So “a”[0] == ?a #=\> true “a”[0] == “a” #=\> false Now, things have changed in the String world in Ruby 1.9. Strings now know their encoding and return charactes instead of codepoints when accessing single characters. “a”[0] #=\> “a” To make sure that legacy applications do not break, ?a will now return “a”, so now the behaviour is as follows: “a”[0] == ?a #=\> true “a”[0] == “a” #=\> true Regards, Florian G. ---
**Author:** ![ghostrifle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f04885/32.png) [@ghostrifle](https://www.ruby-forum.com/u/ghostrifle)\ **Post date:** [March 1, 2010, 6:40pm UTC](https://www.ruby-forum.com/t/what-is-in-ruby/184361/4 "2010-03-01T18:40:29Z")
Florian G. wrote: > On Mar 1, 2010, at 1:31 PM, Alexander Bubnov wrote: > > Ruby 1.8 sees strings as a sequence of bytes. So > > “a”[0] #=\> 97 > > yields 97 (because 97 is the value representing the character a in an > ASCII-String). If you want to compare this to some character, you need > the character code of “a” (because no one wants to have an ASCII-Table > next to them when programming). ?a gives you the character code of a. So > > “a”[0] == ?a #=\> true > “a”[0] == “a” #=\> false > > Now, things have changed in the String world in Ruby 1.9. Strings now > know their encoding and return charactes instead of codepoints when > accessing single characters. > > “a”[0] #=\> “a” > > To make sure that legacy applications do not break, ?a will now return > “a”, so now the behaviour is as follows: > > “a”[0] == ?a #=\> true > “a”[0] == “a” #=\> true > > Regards, > Florian G. Thank you! Have you ever see something about ‘?’ in specification of ruby1.9? If so can you please point to that doc. Unfortunately I cannot find anything about it but I would like to know it because, for example, in ruby1.10 it can be changed in once day. ---
**Author:** ![ghostrifle](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f04885/32.png) [@ghostrifle](https://www.ruby-forum.com/u/ghostrifle)\ **Post date:** [March 1, 2010, 6:43pm UTC](https://www.ruby-forum.com/t/what-is-in-ruby/184361/5 "2010-03-01T18:43:21Z")
> Thank you! Have you ever see something about ‘?’ in specification of > ruby1.9? If so can you please point to that doc. Unfortunately I cannot > find anything about it but I would like to know it because, for example, > in ruby1.10 it can be changed in once day. Many thanks to all! I am sorry I did not see post about documentation! Now it is clear!