  The production of charm quark jets in association with electroweak gauge
bosons at the LHC can be used as a tool to constrain quark parton distribution
functions (PDFs). Motivated by recent measurements at the Tevatron and LHC, we
calculate cross sections for $W/Z+c$, comparing these to $W/Z+\textrm{jet}$,
for various PDF sets. The cross-section differences can be understood in terms
of the different underlying PDFs, with the strange quark distribution being
particularly important for $W+c$ production. We suggest measurements of
appropriately defined ratios and comment on how these measurements at the LHC
can be used to extract information on the strange and charm content of the
proton at high $Q^2$ scales.
