erator_sub.html" title="operator-">db_vector_base_iterator::operator-(difference_type n) const</a>
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difference_type operator-(const self &amp;itr) const
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        <p>Iterator distance operator. </p>
        <p>Return the index difference of this iterator and itr, so if this iterator sits on an element with a smaller index, this call will return a negative number. </p>
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