how C output LF to stdout without being changed to CR LF?

The MSVC solution is:

#include <io.h>#include <fcntl.h>..._setmode(1,_O_BINARY)

Other runtimes may provide the C99 solution or an alternate way. EDIT: I believe setmode([file number],O_BINARY) originated on Borland Turbo C, and other compilers for MS-DOS and Windows imitated it. The _ prefix is done to keep the namespace clean, and may not be present on some compilers.

A text file converts the C character '\n' into the native line ending on output, and converts the native line ending on input into a single '\n'.

To get the result you require, you'd have to change stdout into a binary file stream.

A partial answer is found here. If you have a C99-compliant library, using:

if (freopen(0, "wb", stdout) == 0)    ...oops...operation failed...

will attempt to change standard output to a binary stream. However, on Windows, the 'C99-compliant library' might be a problem. Nominally, this is the portable (because standard) answer. There is likely a Windows-specific function to do the same job.

#ifdef _WIN32#include <fcntl.h>#include <io.h>#endif#ifdef __BORLANDC__#define _setmode setmode#endif#include <stdio.h>static void binary_stdout(void) {#ifdef _WIN32    _setmode(_fileno(stdout), _O_BINARY);#endif}int main(void) {    binary_stdout();    printf("\n");    return 0;}