Hello *,<div><br></div><div>I really enjoyed working with Iostreams, while testing some of my components. Using IOStreams with array_device seemed to be a very powerfull approach to test some of my stream based algorithms. But currently I face some issues which seem to be really weired to me. I produced some code snippet to better explain it. I used Boost.Test library to verify my assumptions.</div>

<div><br></div><div>    using namespace boost;</div><div>    namespace io=boost::iostreams; </div><div>   </div><div>    typedef unsinged char byte;</div><div><div>    typedef array&lt;byte, 2&gt; arr_buffer;  //boost::array</div>

<div>    typedef io::basic_array&lt;byte&gt; arr_dev;</div><div><br></div><div>    arr_buffer buffer_ = {{}};</div><div>    arr_dev dev_(buffer_.begin(), buffer_.end());</div><div>    io::stream&lt;arr_dev&gt; ios_(dev_);</div>

<div><br></div><div><div>    arr_dev::pair_type range = dev_.input_sequence();</div><div>    BOOST_MESSAGE(&quot;size: &quot; &lt;&lt; distance(range.first, range.second)); // output: size is 2</div></div><div><br></div>
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<br></div><div>    BOOST_CHECK_EQUAL(0u, ios_.tellg());  //stream is at position 0 as expected</div><div>    ios_.seekg(1);</div><div>    BOOST_CHECK_EQUAL(1u, ios_.tellg()); // stream is at position 1 as expected</div><div>

    ios_.seekg(2);</div><div>    BOOST_MESSAGE(&quot;current pos: &quot; &lt;&lt; ios_.tellg()); // !!! stream is at position 2</div><div>    ios_.seekg(3);</div><div>    BOOST_MESSAGE(&quot;current pos: &quot; &lt;&lt; ios_.tellg()); // stream is at position -1</div>

<div>    BOOST_MESSAGE(&quot;eof: &quot; &lt;&lt; ios_.eof()); // !!! but eof is false</div><div><br></div><div><br></div><div>If the defined stream is only 2 bytes long why is 2 a valid stream position? Why is eof always false? Do you think this behavior is buggy?</div>

<div><br></div><div>I changed the same behavior to read bytes from stream and created an array of length 3, but passed the range of 2 bytes to the device ctor. This works as expected:</div><div><br></div><div><div>    arr_buffer buffer_ = {{&#39;a&#39;, &#39;b&#39;, &#39;c&#39;}};</div>

<div>    arr_dev dev_(buffer_.begin(), buffer_.begin()+2); //range of 2 bytes is passed</div><div>    io::stream&lt;arr_dev&gt; ios_(dev_);</div><div><br></div><div>    arr_dev::pair_type range = dev_.input_sequence();</div>

<div>    BOOST_MESSAGE(&quot;size: &quot; &lt;&lt; distance(range.first, range.second));</div><div><br></div><div>    byte bt;</div><div><br></div><div>    BOOST_MESSAGE(&quot;current pos: &quot; &lt;&lt; ios_.tellg()); // prints 0</div>

<div>    BOOST_CHECK_EQUAL(0u, ios_.tellg());</div><div>    ios_.read(&amp;bt, 1);</div><div>    BOOST_MESSAGE(&quot;retrieved: &quot; &lt;&lt; bt);   // prints &#39;a&#39;</div><div><br></div><div>    BOOST_MESSAGE(&quot;current pos: &quot; &lt;&lt; ios_.tellg()); //prints 1</div>

<div>    BOOST_CHECK_EQUAL(1u, ios_.tellg());</div><div>    ios_.read(&amp;bt, 1);</div><div>    BOOST_MESSAGE(&quot;retrieved: &quot; &lt;&lt; bt); // prints &#39;b&#39;</div><div><br></div><div>    BOOST_MESSAGE(&quot;current pos: &quot; &lt;&lt; ios_.tellg()); // !!! prints 2, why not -1???</div>

<div>    ios_.read(&amp;bt, 1);</div><div>    BOOST_MESSAGE(&quot;retrieved: &quot; &lt;&lt; bt); // still prints &#39;b&#39; =&gt; nothing retrieved</div><div>    BOOST_MESSAGE(&quot;current pos: &quot; &lt;&lt; ios_.tellg());  // !!! now it prints -1</div>

<div>    BOOST_MESSAGE(&quot;eof: &quot; &lt;&lt; ios_.eof()); // !!! now eof is true</div></div><div><br></div><div>Any ideas why it behaves as described?</div><div><br></div><div><br></div><div>With Kind Regards,</div>
<div>
Ovanes</div><div><br></div><div><br></div></div>