////
Copyright 2021 Glen Joseph Fernandes
(glenjofe@gmail.com)

Distributed under the Boost Software License, Version 1.0.
(http://www.boost.org/LICENSE_1_0.txt)
////

# Null Streams, <boost/io/nullstream.hpp>
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## Description

The header `<boost/io/nullstream.hpp>` provides the class template
`boost::io::basic_nullbuf` which is a null stream buffer and class template
`boost::io::basic_onullstream` which is a null stream.

## Example

The following program passes a null stream to a function.

```
#include <boost/io/ostream_joiner.hpp>
#include <fstream>

void setup(std::ostream& log);

int main(int argc, char* argv[])
{
    if (argc == 2) {
        std::ofstream file(argv[1]);
        setup(file);
    } else {
        boost::io::onullstream none;
        setup(none);
    }
}
```

## Reference

### Header Synopsis

```
namespace boost {
namespace io {

template<class CharT, class Traits = std::char_traits<Char> >
class basic_nullbuf
    : public std::basic_streambuf<CharT, Traits> {
protected:
    typename Traits::int_type overflow(typename Traits::int_type c) override;

    std::streamsize xsputn(const CharT*, std::streamsize n) override;
};

template<class CharT, class Traits = std::char_traits<CharT> >
class basic_onullstream
    : public std::basic_ostream<CharT, Traits> {
public:
    basic_onullstream();
};

typedef basic_onullstream<char> onullstream;
typedef basic_onullstream<wchar_t> wonullstream;

} // io
} // boost
```

## Acknowledgments

Glen Fernandes implemented `basic_nullbuf` and `basic_onullstream`.
