4.2.3 GetAtom, GetBond

The GetAtom and GetBond function return a pointer to a single OEAtomBase or OEBondBase. The pointer returned is the first instance in the molecule of and atom or bond for which the predicate function (vida infra) passed into these functions as an argument returns true.

Thus mol.GetBond(HasOrder(2)) will return a pointer to the first double-bond in the molecule.