Here is the code I am using to copy an MP3 file from the read-only part of the application (APK, or whatever) to the writable part.
You might be able to use it.
unsigned long tmpSize;
string fullPath = CCFileUtils::sharedFileUtils()->fullPathFromRelativePath("data.mp3");
unsigned char* xmlData = CCFileUtils::sharedFileUtils()->getFileData(fullPath.c_str(), "rb", &tmpSize);
FILE *fp = fopen(dbPath.c_str(), "wb");
fwrite(xmlData, tmpSize, 1, fp);
This reads and writes binary files. You’ll want to change the ‘rb’ and ‘wb’ to ‘r’ and ‘w’ probably.
There are many ways to copy one file to another file in C++