columnstableswidth
I would like that the width of the first column of an array to be 2cm and the second column to be 1cm. I have the following document but apparently the setting for the width of the second column is not working.
\documentclass{book}
\usepackage{multicol}
\begin{document}
\begin{multicols}{2}
\noindent
\begin{tabular}{ p{2cm} l p{1cm} r}
abc abc abc abc & xyz xyz xyz xyz xyz \\
\end{tabular}
\end{multicols}
\end{document}
The problem is that the \begin{...} and \end{...} pair commands automatically create a "group" so that, in effect, the & and \\ are "out of scope" for the tabular, while inside the "production" environment they just show up at a place where the compiler is not expecting them.
A second problem with your definitions is that, even if they would work, they would be adding an extra \\ at the end of the tabular, adding an unwanted space at the end. Perhaps some more appropriate definitions would be
\documentclass[a4paper,10pt]{article}
\newcommand{\production}[1]{#1 ::= &}
\newenvironment{grammar}{\tabular{p{3cm}l}}{\endtabular}
\begin{document}
\begin{grammar}
\production{XmlStartTag} ... \\
\production{XmlOtherTag} ... \\
\production{XmlEndTag} ...
\end{grammar}
\end{document}
Note no \\ at the end of the last production. Also in the definition of the grammar you don't need to repeat the work of \begin/\end, and you can instead directly use \tabular and \endtabular.
\documentclass[11pt]{article}
\usepackage{array,ragged2e}
\newcolumntype{C}[1]{>{\Centering}m{#1}}
\begin{document}
{\def\arraystretch{1.5}
\begin{tabular}{ C{1.8cm} | C{1cm} }
Problem & $\beta$ \\\hline
LCR-1 & 0.25 \\\hline
LCR-10 & 0.05 \\\hline
LCR-0.2 & 0.575 \\\hline
Airplane & 0.05 \\\hline
DR & 0.27
\end{tabular}}
\end{document}
Best Answer
The problem is the unnecessary
lanndrin\begin{tabular}{ p{2cm} l p{1cm} r}:Update: Regarding aligning the second column right, I recommend reading this answer