For std::stream / ostream / istream / ...: What is the difference between using operators << and >> or using write() and read() methods ?
I suppose for binary writing/reading you should use write/read, but Is there any difference for text/ASCII ?
write and read do not understand anything about the data being printed - for them all there is are bytes. << and >> on the other hand understand what you print and can be overloaded only for a given datatype. As a consequence read and write are generally faster - no complex logic happens, we simply print bytes to the stream.
read and write themselves are certainly faster, but because they deal in unformatted data, we have to add formatting functions to insert data into and extract it out of the buffer. (Admittedly, formatting binary data is typically faster than formatting text, but you still can't ignore it completely.)