How to make cout behave as in binary mode?
Solution 1:
This works using Visual Studio 2013:
#include <io.h>
#include <fcntl.h>
#include <iostream>
int main( int argc, char * argv[] )
{
_setmode( _fileno( stdout ), _O_BINARY );
std::cout << std::endl;
}
It will output only [0A], and not [0D][0A].
Solution 2:
I don't believe you can force std::cout
to output binary data. The lowest-level interface available to the user through C++ is the streambuf
at std::cout.rdbuf()
. You can pretty well assume that object is of type basic_filebuf
, and section §27.9.1.4 of the C++11 standard requires that basic_filebuf
implement separate text and binary modes.
Check your platform-specific extensions for a way to open another stream to stdout
using its file descriptor. Then you can specify std::binary
in the mode flags.
However, it's probably easier to pipe the output through a second program that converts the line endings.
Edit: Now I see that you might be willing to go a little further to truly make the program directly output what you want.
You can use the C interface to output newlines as long as the C++ interface is set to unbuffered mode.
At the very beginning of your program, before cout
receives any output, do this:
std::cout.rdbuf()->pubsetbuf( 0, 0 ); // go to unbuffered mode
When you want to output a newline, do it like so:
_write( STDOUT_FILENO, 1, "\n" ); // do not convert line ending
You can wrap this little… nugget… inside a custom manipulator:
#include <unistd.h>
std::ostream &endln( std::ostream &s ) {
if ( s->rdbuf() == std::cout.rdbuf() ) { // this is cout or cerr into cout
_write( STDOUT_FILENO, 1, "\n" ); // do not convert line ending
return s; // stream is unbuffered, no need to flush
} else {
return std::endl( s ); // other streams do convert to \r\n
}
}