# H() doesn't have any parameter for encoding being used?

**URL:** <https://www.ruby-forum.com/t/h-doesnt-have-any-parameter-for-encoding-being-used/149682>\
**Category:** Rails\
**Created:** [September 28, 2008, 5:01am UTC](https://www.ruby-forum.com/t/h-doesnt-have-any-parameter-for-encoding-being-used/149682 "2008-09-28T05:01:35Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![winterheat](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/7993a0/32.png) [@winterheat](https://www.ruby-forum.com/u/winterheat)\
**Post date:** [September 28, 2008, 5:01am UTC](https://www.ruby-forum.com/t/h-doesnt-have-any-parameter-for-encoding-being-used/149682/1 "2008-09-28T05:01:35Z")

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it seems that there is no parameter for the function h() (html\_escape())  
to indicate the character encoding being used?

for PHP, its htmlspecialchars() function has a dozen encoding possible,  
such as UTF-8, Chinese Big5, Chinese GB, Russia, Japanese.

i think thought, h() will work for UTF-8, since h() will only touch the  
4 special characters

\< \> & "

and replace them with \< etc and those 4 characters are all in the  
0x00 to 0x7F range, and h() will leave the other bytes intact  
(unchanged). Now, since a character in UTF-8 can be 1 to 4 bytes, and  
that any ASCII will be represented as 1 byte, which is 0x00 to 0x7F  
itself, and that 0x80 to 0xFF and other unicode characters will be 2 to  
4 bytes long, but with the 1st to 4th bytes all being in the 0x80 to  
0xFF range (see UTF-8 [UTF-8 - Wikipedia](http://en.wikipedia.org/wiki/Utf-8) ), so when h()  
replaces those 4 ASCII characters, it will successfully do so when h()  
sees those 4 characters as a 1-byte character, and then it will bypass  
all the 1st to 4th bytes characters because those characters are in the  
0x80 to 0xFF range, and therefore can never be matched as one of those 4  
special characters, so the job of replacing those 4 characters will be  
done with no side effect whatsoever done to the non-ASCII characters.

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<div class="post-metadata">

**Author:** ![winterheat](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/7993a0/32.png) [@winterheat](https://www.ruby-forum.com/u/winterheat)\
**Post date:** [September 28, 2008, 6:18am UTC](https://www.ruby-forum.com/t/h-doesnt-have-any-parameter-for-encoding-being-used/149682/2 "2008-09-28T06:18:10Z")

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## I don’t think Rails supports UTF8 yet… but I could be wrong.

Ryan B.  
Freelancer

> **[frozenplague.net](http://frozenplague.net)**
>
> This domain may be for sale!

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<div class="post-metadata">

**Author:** ![winterheat](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/7993a0/32.png) [@winterheat](https://www.ruby-forum.com/u/winterheat)\
**Post date:** [September 28, 2008, 11:22am UTC](https://www.ruby-forum.com/t/h-doesnt-have-any-parameter-for-encoding-being-used/149682/3 "2008-09-28T11:22:53Z")

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On Sat, Sep 27, 2008 at 9:18 PM, Ryan B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> I don’t think Rails supports UTF8 yet… but I could be wrong.

The default charset for action renderings is UTF-8 since Rails 1.2.

-Conrad

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<div class="post-metadata">

**Author:** ![winterheat](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/7993a0/32.png) [@winterheat](https://www.ruby-forum.com/u/winterheat)\
**Post date:** [September 28, 2008, 9:14pm UTC](https://www.ruby-forum.com/t/h-doesnt-have-any-parameter-for-encoding-being-used/149682/4 "2008-09-28T21:14:10Z")

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On Sun, Sep 28, 2008 at 5:01 AM, SpringFlowers AutumnMoon  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> 0x80 to 0xFF range, and therefore can never be matched as one of those 4  
> special characters, so the job of replacing those 4 characters will be  
> done with no side effect whatsoever done to the non-ASCII characters.

Ruby 1.8 has a global idea of character enconding, which is configured  
in the $KCODE global variable.

Rails 1.2 and above by default set $KCODE to a value that means  
everything is UTF-8. Source code, strings, regexps, etc. It also sets  
a HTTP header that tells the client (X)HTML goes as UTF-8. Thus, the  
client sends form data back in UTF-8 as well. And everything works  
transparently.

When you do I/O you are responsible for knowing the encoding of  
incoming data, and the expected encoding of outgoing data. You use  
iconv if needed to guarantee them. Any I/O operation has to be in  
control of the involved character encodings.

Some stuff in Ruby 1.8 does not play well with UTF-8, for example you  
cannot compute the length of a string with String#length because that  
method counts bytes. But some other stuff do work, like pattern  
matching. For example “.” really matches a character, which may not be  
a byte in UTF-8, as you point out.

So, if you are using regexps you are safe in that regard. The helper  
#h is really an ERb alias of the ERb method #html\_escape (it is not a  
Rails helper), and that method is implemented using regexps:

def html\_escape(s)  
s.to\_s.gsub(/&/, “&”).gsub(/"/, “"”).gsub(/\>/,  
“\>”).gsub(/\</, “\<”)  
end

Hence, it works correctly in UTF-8.