Re: [Cppcms-users] Questions about decode UTF-8 to Unicode code point

[Artyom B. <art...@ya...>]

First of all there is utf_to_utf functions and if sizeof(wchar_t) == 4 (which is on Linux/Unix)
than all you need is to use them.

About the error

code_point c = utf_traits<char, sizeof(char)>::decode(str.begin(), str.end());


the first parameter is reference that is moved forward and std.begin() can't be changed
so what you need to do is:


std::string::const_iterator pos = std.begin(),end =str.end();
code_point c = utf_traits<char, sizeof(char)>::decode(pos,end );


See: http://www.boost.org/doc/libs/1_51_0/libs/locale/doc/html/structboost_1_1locale_1_1utf_1_1utf__traits.html#a65f0b0e1075dd000d2c2c15af30be372
 
Artyom Beilis
--------------
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>________________________________
> From: 陈抒 <csf...@gm...>
>To: cpp...@li... 
>Sent: Tuesday, February 5, 2013 5:32 PM
>Subject: [Cppcms-users] Questions about decode UTF-8 to Unicode code point
> 
>
>Hello Artyom:
>  I am using the boost.locale library contributed by you to decode UTF-8.
>The following codes works fine:
>char const * p = "一"; // one Chinese character here
>
>code_point c = utf_traits<char, sizeof(char)>::decode(p, p + 3);
>cout << "code point: 0x" << std::hex << c << " binary format:B" << PrintIntAsBinaryString(c) << endl;
>
>
>My Print.. function prints it as what I expect.
>code point: 0x4e00 binary format:B00000000000000000100111000000000
>
>
>
>But don't know how to apply the decode function to std::string. when using iterator of string object, got some compilation error:
>
>
>string str = "一";
>
>code_point c = utf_traits<char, sizeof(char)>::decode(str.begin(), str.end());
>
>
>
>/home/chenshu/work/asio_echo/codes/main/test/main.cc:18:65: error: no matching function for call to ‘boost::locale::utf::utf_traits<char>::decode(std::basic_string<char>::iterator, std::basic_string<char>::iterator)’
>/home/chenshu/work/asio_echo/codes/main/test/main.cc:18:65: note: candidate is:
>/usr/include/boost/locale/utf.hpp:193:27: note: static boost::locale::utf::code_point boost::locale::utf::utf_traits<CharType, 1>::decode(Iterator&, Iterator) [with Iterator = __gnu_cxx::__normal_iterator<char*, std::basic_string<char> >, CharType = char, boost::locale::utf::code_point = unsigned int]
>/usr/include/boost/locale/utf.hpp:193:27: note:   no known conversion for argument 1 from ‘std::basic_string<char>::iterator {aka __gnu_cxx::__normal_iterator<char*, std::basic_string<char> >}’ to ‘__gnu_cxx::__normal_iterator<char*, std::basic_string<char> >&’
>make[2]: *** [test_bin/CMakeFiles/util_test.dir/main.cc.o] Error 1
>make[1]: *** [test_bin/CMakeFiles/util_test.dir/all] Error 2
>make: *** [all] Error 2
>
>
>The above is my first question, that's about converting one single Unicode character.
>Another question is how to decode all Unicode code points from string object?
>
>
>
>陈抒 
>Best regards
>http://blog.csdn.net/sheismylife
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