datastream_methods_utility"></a></p>
    <h5>Object verification</h5>
    <dl>
      <dt><strong> virtual int valid()</strong></dt>
      <dd>Checks input datastream validity. Returns 1 on valid stream and 0 if
        datastream was created on non-valid input parameters (wrong filename for
        file stream and so on).</dd>
    </dl>
    <p><a name="datastream_methods_read"></a></p>
    <h5>Stream read and positioning</h5>
    <p>This group of methods implements file object (FILE*) semantics.</p>
    <dl