_setmode
Sets the file translation mode.
Syntax
int _setmode (
int fd,
int mode
);
Parameters
fd
File descriptor.
mode
New translation mode.
Return value
If successful, returns the previous translation mode.
If invalid parameters are passed to this function, the invalid-parameter handler is invoked, as described in Parameter validation. If execution is allowed to continue, this function returns -1 and sets errno
to either EBADF
, which indicates an invalid file descriptor, or EINVAL
, which indicates an invalid mode
argument.
For more information about these and other return codes, see errno
, _doserrno
, _sys_errlist
, and _sys_nerr
.
Remarks
The _setmode
function sets to mode
the translation mode of the file given by fd
. Passing _O_TEXT
as mode
sets ANSI text (that is, translated) mode. Carriage return-line feed (CR-LF) combinations are translated into a single line feed character on input. Line feed characters are translated into CR-LF combinations on output. Passing _O_BINARY
sets binary (untranslated) mode, in which these translations are suppressed.
You can also pass _O_U16TEXT
, _O_U8TEXT
, or _O_WTEXT
to enable Unicode mode, as demonstrated in the second example later in this document.
Caution
Unicode mode is for wide print functions (for example, wprintf
) and is not supported for narrow print functions. Use of a narrow print function on a Unicode mode stream triggers an assert.
_setmode
is typically used to modify the default translation mode of stdin
and stdout
, but you can use it on any file. If you apply _setmode
to the file descriptor for a stream, call _setmode
before you perform any input or output operations on the stream.
Caution
If you write data to a file stream, explicitly flush the code by using fflush
before you use _setmode
to change the mode. If you do not flush the code, you might get unexpected behavior. If you have not written data to the stream, you do not have to flush the code.
By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.
Requirements
Routine | Required header | Optional Headers |
---|---|---|
_setmode |
<io.h> |
<fcntl.h> |
For more compatibility information, see Compatibility.
Example: Use _setmode
to change stdin
// crt_setmode.c
// This program uses _setmode to change
// stdin from text mode to binary mode.
#include <stdio.h>
#include <fcntl.h>
#include <io.h>
int main( void )
{
int result;
// Set "stdin" to have binary mode:
result = _setmode( _fileno( stdin ), _O_BINARY );
if( result == -1 )
perror( "Cannot set mode" );
else
printf( "'stdin' successfully changed to binary mode\n" );
}
'stdin' successfully changed to binary mode
Example: Use _setmode
to change stdout
// crt_setmodeunicode.c
// This program uses _setmode to change
// stdout to Unicode. Cyrillic and Ideographic
// characters will appear on the console (if
// your console font supports those character sets).
#include <fcntl.h>
#include <io.h>
#include <stdio.h>
int main(void) {
_setmode(_fileno(stdout), _O_U16TEXT);
wprintf(L"\x043a\x043e\x0448\x043a\x0430 \x65e5\x672c\x56fd\n");
return 0;
}
See also
File handling
_creat
, _wcreat
fopen
, _wfopen
_open
, _wopen
_set_fmode