How to set zero margin around tabular of textwidth?

Question

\begin{tabular*}{ \textwidth{l@{\extracolsep{\fill}}r} a & b \end{tabular*}

I need to fit a tabular to textwidth with zero left and right margins. The code above allows to fit the text to table width, but I don't know how to set the left and right margins to zero.

Answer 1

\documentclass{article}
\begin{document}
\begin{tabular*}{\textwidth}{@{}l@{\extracolsep{\fill}}r@{}}%
\hline a&b\\\hline 
 \end{tabular*}
\end{document}

Of course, if the table is not in a float (a table environment) and \partindent is not 0pt (the default) as in this MWE, remember add \noindent before the tabular* environment to maintain it between the page margins.

If you refer to extend the table to the page margins, as L. Nielsen suspected, the trick is put the table in a centered box of zero space, and of course, make the table enough big:

\documentclass{article}
\usepackage{geometry}
\begin{document}
\centering\makebox[0cm]{%
\begin{tabular*}{\paperwidth}{@{}l@{\extracolsep{\fill}}r@{}}%
\hline a&b\\\hline% 
 \end{tabular*}}%
\end{document}