I cannot seem to make \hhline draw vertical lines between cells. What am I missing?
\documentclass[a4paper,11pt]{article}
\usepackage{hhline}
\begin{document}
\begin{tabular}{cc}
A & B \\ \hhline{~|-}
C & D \\ \hhline{~|-|}
\end{tabular}
\end{document}

\hhlineis defined to produce only horizontal lines (the "h" in the command). If you want vertical lines separating all the cells, enter the template as{c|c}. If you want them on the outside edges as well, use{|c|c|}. – barbara beeton Apr 15 '19 at 18:11