Question

What would be the algorithm/implementation of the C++ code C++functionX in the following flow chart:

(JavaString) --getBytes--> (bytes) --C++functionX--> (C++String)

JavaString contents should match C++String contents as far as possible (preferably 100% for all possible values of JavaString)

[EDIT] The endianness of bytes can be ignored as there are ways to handle that.

Answer 1

Java:

String original = new String("BANANAS");
byte[] utf8Bytes = original.getBytes("UTF8");
//save the length as a 32 bit integer, then utf8 Bytes to a file

C++:

int32_t tlength;
std::string utf8Bytes;
//load the tlength as a 32 bit integer, then the utf8 bytes from the file
//well, that's easy for UTF8

//to turn that into a utf-18 string in windows
int wlength = MultiByteToWideChar(CP_UTF8, 0, utf8Bytes.c_str(), utf8Bytes.size(), nullptr, 0);
std::wstring result(wlength, '\0');
MultiByteToWideChar(CP_UTF8, 0, utf8Bytes.c_str(), utf8Bytes.size(), &result[0], wlength);
//so that's not hard either

To do this in linux, one uses the iconv library, which is incredibly powerful, but more difficult to use. Here’s a function that converts a std::string in UTF8 to a std::wstring in UTF32: http://coliru.stacked-crooked.com/view?id=986a4a07e391213559d4e65acaf231d5-e54ee7a04e4b807da0930236d4cc94dc