Question

I need to implement this Java code in (unmanaged) c++:

byte[] b = string.getBytes("UTF8");

I’m new to c++, and can’t find anything to do this. It has to be platform independent, if possible. Using c++11 compiler.

Answer 1

Java String is roughly equivalent to std::u16string, a specialization of std::basic_string. I suggest you try something like…

std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t> convert;
std::string converted = convert.to_bytes(u"HELLO, WORLD!");
const char *bytes = converted.data();

Note this relies on C++11; it might be sometime before your compiler vendor fully supports these features.

Here, we utilize the newly introduced std::wstring_convert to convert from a wide-character UTF-16 string to the UTF-8 multibyte string via to_bytes (it also supports conversion in the other direction, too).

This is made possible via the (also newly introduced) std::codecvt_utf8_utf16 conversion facet. It takes care of the actual conversion for us nicely.

Besides that, it makes use of the new character literal prefixes added with C++11 — in particular, u, which is for char16_t UTF-16 strings 🙂 There are also u8 and U for UTF-8 and UTF-32, respectively.

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PS data is (as of C++11) guaranteed to be equal to c_str and therefore can be relied upon to be NUL-terminated.