UnicodeString to char* (UTF-8)

问题

I am using the ICU library in C++ on OS X. All of my strings are UnicodeStrings, but I need to use system calls like fopen, fread and so forth. These functions take const char* or char* as arguments. I have read that OS X supports UTF-8 internally, so that all I need to do is convert my UnicodeString to UTF-8, but I don't know how to do that.

UnicodeString has a toUTF8() member function, but it returns a ByteSink. I've also found these examples: http://source.icu-project.org/repos/icu/icu/trunk/source/samples/ucnv/convsamp.cpp and read about using a converter, but I'm still confused. Any help would be much appreciated.

回答1:

call UnicodeString::extract(...) to extract into a char*, pass NULL for the converter to get the default converter (which is in the charset which your OS will be using).

回答2:

ICU User Guide > UTF-8 provides methods and descriptions of doing that.

The simplest way to use UTF-8 strings in UTF-16 APIs is via the C++ icu::UnicodeString methods fromUTF8(const StringPiece &utf8) and toUTF8String(StringClass &result). There is also toUTF8(ByteSink &sink).

And extract() is not prefered now.

Note: icu::UnicodeString has constructors, setTo() and extract() methods which take either a converter object or a charset name. These can be used for UTF-8, but are not as efficient or convenient as the fromUTF8()/toUTF8()/toUTF8String() methods mentioned above.

回答3:

This will work:

std::string utf8;
uStr.toUTF8String(utf8);

来源：https://stackoverflow.com/questions/3150581/unicodestring-to-char-utf-8