[Tex/LaTex] Table in landscape mode

Question

I would to make the table in landscape mode. To do that, I used pdflscape package. But I couldn't get the desired result. How to do that?

Here is the MWE:

\documentclass[12pt]{article}
\usepackage{xtab,caption}
\usepackage{pdflscape}
\newcommand\Lenv{\textsf}
\begin{document}
\begin{landscape}
\topcaption{The principal xtab package commands} \label{tab:xtab}
\tablefirsthead{\hline \multicolumn{1}{|c|}{\textbf{Command}} &
\multicolumn{1}{c|}{\textbf{Effect}} \\ \hline }
\tablehead{\multicolumn{2}{c}%
{{\captionsize\bfseries \tablename\ \thetable{} --
continued from previous page}} \\
\hline \multicolumn{1}{|c|}{\textbf{Command}} &
\multicolumn{1}{c|}{\textbf{Effect}} \\ \hline }
\tablelasthead{\multicolumn{2}{c}%
{{\captionsize\bfseries \tablename\ \thetable{} --
concluded from previous page}} \\
\hline \multicolumn{1}{|c|}{\textbf{Command}} &
\multicolumn{1}{c|}{\textbf{Effect}} \\ \hline }
\tabletail{\hline \multicolumn{2}{|r|}{{Continued on next page}} \\ \hline}
\tablelasttail{\hline \hline}
\begin{center}
\begin{xtabular}{|l|p{0.5\textwidth}|}
\verb|\begin{xtabular}{...}| & This is equivalent to the normal
\verb|\begin{tabular}{...}| environment.
You supply the specification of the columns
just as for the normal \Lenv{tabular} environment.
\\
&
All commands that can be used within a \Lenv{tabular}
environment can also be used within
the \Lenv{xtabular} environment.
\\
&
Unlike the \Lenv{tabular} environment which prevents page breaking
within the tabular, the \Lenv{xtabular} allows page breaking, so that
tabulars can extend automatically across several pages.
... ... ...\\
\verb|\tablelasttail{...}| & The contents of this command are inserted before
the final (internal) \verb|\end{tabular}| of the table.
\\
&
For example, you might want to note that this is where
the table ends.
\\
\end{xtabular}
\end{center}
\end{landscape}
\end{document} 

Answer 1

use

 \begin{xtabular}{|l|p{0.5\linewidth}|}

lscape does not change \textwidth in the landscape environment.