C ++ streaming to char array?

Question

im is currently working on a C ++ application that uses the c library, which requires a callback implemented by me, for example, a callback is defined as follows:

int onWrite(char *what, char *buffer, size_t size, off_t offset);

I have std :: set, which needs to be formed and written to the buffer, and take care of the size and offset, where size is the size of the buffer and the offset, how many bytes are already processed

is there a C ++ way where I can use a stream in a buffer? I am thinking of something like this:

SomeSTLStandardStream stream(buffer,size);
stream.ignore(offset);  // to drop the first n offset bytes
for(it=dataset.begin();it!=dataset.end() && stream.buffer_avail()>0;it++)
    stream << *it << "|"; // format csv like for example

The main question I have is: is there a standard C ++ method for capturing the entire fragment of generated / stream data and writing to a given buffer?

If not bad, I need to execute my own

, , , , , ....

Answer 1

, std::stringstream::pubsetbuf:

 int main()
 {
    char buf[1024];

    std::stringstream stream;

    stream.rdbuf()->pubsetbuf(buf, sizeof(buf));

    stream<< "Hello " << "World " << std::endl;

    std::string str;
    std::getline(stream, str);
    std::cout << str << std::endl;

    //...
}

std::stringstream, std::basic_streambuf std::basic_stringbuf.