  We study one generator quasi-cyclic codes and four-circulant codes, which are
also quasi-cyclic but have two generators. We state the hull dimensions for
both classes of codes in terms of the polynomials in their generating elements.
We prove results such as the hull dimension of a four-circulant code is even
and one-dimensional hull for double-circulant codes, which are special one
generator codes, is not possible when the alphabet size $q$ is congruent to 3
mod 4. We also characterize linear complementary pairs among both classes of
codes. Computational results on the code families in consideration are provided
as well.
