Header File 

fcntl.h 

Syntax 

extern int _fmode; 

Description 

_fmode determines in which mode (text or binary) files will be opened and translated. The value of _fmode is O_TEXT by default, which specifies that files will be read in text mode. If _fmode is set to O_BINARY, the files are opened and read in binary mode. (O_TEXT and O_BINARY are defined in fcntl.h.) 

In text mode, carriage-return/linefeed (CR/LF) combinations are translated to a single linefeed character (LF) on input. On output, the reverse is true: LF characters are translated to CR/LF combinations. 

In binary mode, no such translation occurs. 

You can override the default mode as set by _fmode by specifying a t (for text mode) or b (for binary mode) in the argument type in the library functions fopen, fdopen, and freopen. Also, in the function open, the argument access can include either O_BINARY or O_TEXT, which will explicitly define the file being opened (given by the path argument to the open function) to be in either binary or text mode.