[TIP] File modes
"r" Read from file - YES Write to file - NO Create file if not exists - NO Truncate file to zero length - NO Cursor position - BEGINNING "r+" Read from file - YES Write to file - YES Create file if not exists - NO Truncate file to zero length - NO Cursor position - BEGINNING "w" Read from file - NO Write to file - YES Create file if not exists - YES Truncate file to zero length - YES Cursor position - BEGINNING "w+" Read from file - YES Write to file - YES Create file if not exists - YES Truncate file to zero length - YES Cursor position - BEGINNING "a" Read from file - NO Write to file - YES Create file if not exists - YES Truncate file to zero length - NO Cursor position - END "a+" Read from file - YES Write to file - YES Create file if not exists - YES Truncate file to zero length - NO Cursor position - END