Null device
Narasimha Rao, Mothukuri
I want to redirect my ouput to a null stream. Is there any way to do? My
code looks as follows:
(condition)?(mystream):cnull;
condition - condition which iam checking,
mystream- a stream.
cnull - iam considering a null stream, if i direct any output to that
stream it should do nothing.
Is there any stream like cnull, can i open /dev/null and direct the
output to that?
thanks in advance
M.N.Rao
Paul Lutus
--
Paul Lutus
www.arachnoid.com
Narasimha Rao, Mothukuri wrote in message
<3767B60B...@sesd.cig.mot.com>...
Steve Horne
>
> I want to redirect my ouput to a null stream. Is there any way to do? My
> code looks as follows:
>
>
> Is there any stream like cnull, can i open /dev/null and direct the
> output to that?
Sure, you can open /dev/null if your platform has such a file or
device. It is a non-portable solution that won't work on non-Unix like
systems, though. Also, realize that all the normal file
buffering/writing will take place, so you will have some overhead there,
it's just that the OS will throw away everything after you have written
it.
Hope this helps,
-Steve
Paul Lutus
--
Paul Lutus
www.arachnoid.com
Narasimha Rao, Mothukuri wrote in message
<3767B60B...@sesd.cig.mot.com>...
>
>I want to redirect my ouput to a null stream. Is there any way to do? My
>code looks as follows:
>
>(condition)?(mystream):cnull;
>condition - condition which iam checking,
>mystream- a stream.
>cnull - iam considering a null stream, if i direct any output to that
>stream it should do nothing.
>
>Is there any stream like cnull, can i open /dev/null and direct the
>output to that?
>
>thanks in advance
>M.N.Rao
>
Flavius Sabinus
>"Narasimha Rao, Mothukuri" wrote:
>>
>> I want to redirect my ouput to a null stream. Is there any way to do? My
>> code looks as follows:
>>
>>
>> Is there any stream like cnull, can i open /dev/null and direct the
>> output to that?
>
>device. It is a non-portable solution that won't work on non-Unix like
>systems, though. Also, realize that all the normal file
>buffering/writing will take place, so you will have some overhead there,
>it's just that the OS will throw away everything after you have written
>it.
Most systems have a /dev/null equivalent. NULL: works on VMS and Windoze.
Creating a system-independent NULL would be an easy task. Just create a stream
but that never writes anything.
John - N8086N
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George
>
> I want to redirect my ouput to a null stream. Is there any way to do? My
> code looks as follows:
>
> (condition)?(mystream):cnull;
> condition - condition which iam checking,
> mystream- a stream.
> cnull - iam considering a null stream, if i direct any output to that
> stream it should do nothing.
>
Which language is this?
> Is there any stream like cnull, can i open /dev/null and direct the
> output to that?
>
> thanks in advance
> M.N.Rao
....message ends.....
Dietmar Kuehl
Paul Lutus (nos...@nosite.com) wrote:
: Null streams are platform-dependent. Ask in a platform-specific newsgroup.
Sorry, but I disagree. Although /dev/null is indeed platform specific,
it is easy, not to say trivial, to create a null device in C++. Here is
one for starters:
#include <streambuf>
#include <ostream>
template <class cT, class traits = std::char_traits<cT> >
class basic_nullbuf: public std::basic_streambuf<cT, traits>
{
typename traits::int_type overflow(typename traits::int_type c)
{
return traits::not_eof(c); // indicate success
}
};
template <class cT, class traits = std::char_traits<cT> >
class basic_onullstream: public std::basic_ostream<cT, traits>
{
public:
basic_onullstream():
std::basic_ios<cT, traits>(&m_sbuf),
std::basic_ostream<cT, traits>(&m_sbuf)
{
init(&m_sbuf);
}
private:
basic_nullbuf<cT, traits> m_sbuf;
};
typedef basic_onullstream<char> onullstream;
typedef basic_onullstream<wchar_t> wonullstream;
This code is (except for potential typos, I just typed the code and
haven't tested it) only using features of the C++ standard. Thus, your
redirection is [again (I have noted that on several other articles,
too)] invalid. Please make sure that you only direct stuff which is
really platform specific to other newsgroup!
--
<mailto:dietma...@claas-solutions.de>
<http://www.informatik.uni-konstanz.de/~kuehl/>
I am a realistic optimist - that's why I appear to be slightly pessimistic