  Motivated by recent transport experiments, we theoretically study the quantum
Hall effect in topological semimetal films. Owing to the confinement effect,
the bulk subbands originating from the chiral Landau levels establish energy
gaps that have quantized Hall conductance and can be observed in relatively
thick films. We find that the quantum Hall state is strongly anisotropic for
different confinement directions not only due to the presence of the surface
states but also because of the bulk chiral Landau levels. As a result, we
re-examine the quantum Hall effect from the surface Fermi arcs and chiral modes
in Weyl semimetals and give a more general view into this problem. Besides, we
also find that when a topological Dirac semimetal is confined in its rotational
symmetry axis, it hosts both quantum Hall and quantum spin Hall states, in
which the helical edge states are protected by the conservation of the spin-$z$
component.
