redirect output to /dev/null ?
Rui Maciel
/dev/null?
Thanks in advance,
Rui Maciel
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JC
> Is there any standard output object like cout or cerr that acts like
> /dev/null?
If std::ofstream("/dev/null") is not sufficient, there are other
solutions (it's trivial to implement a null ifstream / ofstream). Have
a look here:
http://www.velocityreviews.com/forums/showpost.php?p=1501892&postcount=2
The rest of the posts in that thread besides that one are generally
uninformative.
I'm pretty sure the null_stream thing mentioned there never made it
into boost, btw. Searching for it yielded some boost peer reviews and
the ones I read did not look too promising.
Jason
Ulrich Eckhardt
> Is there any standard output object like cout or cerr that acts like
> /dev/null?
No.
That said, a stream without a streambuffer doesn't actually write its output
anywhere:
// 1 - redirect output
std::cout.rdbuf(0);
std::cout << "look I'm invisible!";
// 2 - write to sinkless stream
std::ostream out(0);
out << "still can't see me?";
Uli
litb
> Is there any standard output object like cout or cerr that acts like
> /dev/null?
>
There is no such default stream type. You can, however, get that
effect by defining your own null-streambuf that just discards any
characters it is handed over:
template<typename Ch, typename Traits = std::char_traits<Ch> >
struct basic_nullbuf : std::basic_streambuf<Ch, Traits> {
typedef std::basic_streambuf<Ch, Traits> base_type;
typedef typename base_type::int_type int_type;
typedef typename base_type::traits_type traits_type;
virtual int_type overflow(int_type c) {
return traits_type::not_eof(c);
}
};
// convenient typedefs
typedef basic_nullbuf<char> nullbuf;
typedef basic_nullbuf<wchar_t> wnullbuf;
// buffers and streams
nullbuf cnull_obj;
wnullbuf wcnull_obj;
std::ostream cnull(&cnull_obj);
std::wostream wcnull(&wcnull_obj);
Keep the buffers and streams in the same file, to avoid static
initialization order problems. I have seen someone used a not-opened
ofstream to do the same and said that writing to it is a noop, but i
haven't been able to verify that since then. So i would better be on
the safe side writing my own like that. Have fun!
AnonMa...@gmail.com
> /dev/null?
No. But the boost iostreams library have null sources and sinks which
I think will do the trick.
HTH
Jyoti Sharma
> Is there any standard output object like cout or cerr that acts like
> /dev/null?
>
I am not aware of any such standard object. But you can very well redirect it to /dev/null easily and achieve the same effect--probably that is why it is not there.
Regards,
Jyoti
litb
> Rui Maciel wrote:
> > Is there any standard output object like cout or cerr that acts like
> > /dev/null?
>
> No.
>
> That said, a stream without a streambuffer doesn't actually write its output
> anywhere:
>
another guy tell me the source of that? (Not to say i wouldn't believe
you, i just want to read further about it)