Re: [Vala] how can I get the number of unicode points in a string?

[Adam Dingle <adam yorba org>]

On 04/03/2011 06:08 AM, ?????? wrote:
> From: "??????"<pharaoh456 163 com>
> Date: 2011-04-03 18:15:12
> To: "Luca Bruno"<lethalman88 gmail com>
> Subject: Re:Re: [Vala] how can I get the number of unicode points in a string?
>
> At 2011-04-03 16:06:32??"Luca Bruno"<lethalman88 gmail com>  wrote:
>
> > On Sun, Apr 03, 2011 at 03:59:23PM +0800, ?????? wrote:
> > > I see that since 0.11.0 vala string.length returns number of bytes rather than that of unicode characters, 
> > > and string[i] returns only one byte. I wonder how to deal with east Asian character strings.
> > There are other methods in string that deal with utf8. For example
> > char_count() and next_char().
> thank you.
> I find char_count(), get_char() and next_char() in gtk+ document.
> Looks like these methods are not covered in vala tutorial and document.
> Is there something like string[i] for index access to utf8? I didn't get it in docs.

To get the i-th character, you could do this:

str.get_char(str.index_of_nth_char(i));

But the current string methods are designed for iteration by offsets, 
not characters. So you should *not* do this, which will be inefficient:

for (int i = 0 ; i < str.char_count() ; ++i) // don't do this
str.get_char(str.index_of_nth_char(i));

Instead, you want to iterate over the string using get_char() and 
next_char(). This is slightly inconvenient since these functions use 
pointers rather than integer offsets. In Vala trunk, J??rg has just 
committed a new method string.get_next_char() which will make it easier 
to iterate over strings:

// in class string
public bool get_next_char (ref int index, out unichar c);

That isn't in any Vala release yet, though. (In the meantime, you might 
be able to copy and paste his implementation from glib-2.0.vapi in Vala 
trunk.)

adam