How to select nodes from a xml tree that contains a specific children using tinyxml2

Question

From the tree below :

<a>
    <b name = "b1"></b>
    <b name = "b2">
        <c/>
    </b>
    <b name = "b3"></b>
</a>

All the elements in b which have the child element c. In-short how to query the xml tree for the xpath "/b[c]" using tinyxml2.