io.h

The header file contains prototypes for functions that perform low level I/O; that is actions that are unbuffered and unformatted. These functions are:

    close()   dup()      open()    tell()
    creat()   eof()      read()    write()
    dup()     lseek()    sopen()

These functions also allow for the opening and closing of a file, the reading and writing of some number of bytes of data, the positioning or reporting of position within the file, and testing if at the end of file.

The three standard files: stdin, stout, and stderr, are also available as handles: 0, 1, 2. There is a possibility that these low level functions will be eliminated in the future, leaving only the stream I/O functions.