  In this paper we analyze the relativistic quantum motion of charged spin-0
and spin-1/2 particles in the presence of a uniform magnetic field and scalar
potentials in the cosmic string spacetime. In order to develop this analysis,
we assume that the magnetic field is parallel to the string and the scalar
potentials present a cylindrical symmetry with their center on the string. Two
distinct configurations for the scalar potential, $S(r)$, are considered: $(i)$
the potential proportional to the inverse of the polar distance, i.e.,
$S\propto1/r$, and $(ii)$ the potential proportional to this distance, i.e.,
$S\propto r$. The energy spectra are explicitly computed for different physical
situations and presented their dependences on the magnetic field strength and
scalar coupling constants.
