LaTeX: table with variable number of lines

Question

In LaTeX, I can do this:

\begin{tabular}{|p{5ex}|p{5ex}|}\hline
  & \\ \hline
  & \\ \hline
  & \\ \hline
\end{tabular}

But I cannot get a variable number of blank lines this way

\newcommand{\mytable}[1]{
  \begin{tabular}{|p{5ex}|p{5ex}|}\hline
    \multido{}{#1}{%
      &\\\hline
    }% multido
  \end{tabular}
}% mytable
\mytable{10}

or with a counter, even without a command \mytable

\newcounter{count}
\begin{tabular}{|p{5ex}|p{5ex}|}\hline
\whiledo{\value{count}<5}{%
  & \\ \hline
  \stepcounter{count}
}% whiledo
\end{tabular}

Does anybody know why this doesn't work?

Indeed, it is a duplicate of 'copy table row n times'. That is exactly what I wanted, thank you very much for the hint!