Print data, followed by a carriage return and newline, to the File, which must have been opened for writing. Prints numbers as a sequence of digits, each an ASCII character (e.g. the number 123 is sent as the three characters ‘1’, ‘2’, ‘3’).
file.println()
file.println(data)
file.println(data, BASE)
file: an instance of the File class (returned by SD.open()).data: the data to print (char, byte, int, long, or string).BASE (optional): the base in which to print numbers; BIN for binary (base 2), DEC for decimal (base 10), OCT for octal (base 8), HEX for hexadecimal (base 16).The number of bytes written, though reading that number is optional.