// using C++11 range-based for loop
ReadAccuracyQuery query(0.9, Compare::GREATER_THAN_EQUAL, dataset);
for (const BamRecord& r : query) {
    assert(r.ReadAccuracy() >= 0.9);
}

// OR

// using iterators directly
ReadAccuracyQuery query(0.9, Compare::GREATER_THAN_EQUAL, dataset);
auto iter = query.cbegin();
auto end  = query.cend();
for (; iter != end; ++iter) {
    assert(iter->ReadAccuracy() >= 0.9);
}