I'm facing an error while compiling and have already included the necessary packages. O want the three columns to be 15 % 70 % 15% respectively and the first two left aligned with the third right aligned. However, I'm facing issues compiling and checked other error troubleshoots but those solutions didn't work.

Package array Error: Illegal pream-token (1): `c' used. ...extwidth} 1{.7\textwidth} r{.15\textwidth}}
\begin{longtable}[h]{l{.15\textwidth} l{.7\textwidth} r{.15\textwidth}} 
        \textbf{Symbol} & \textbf{Description} & \textbf{Units} \\ \hline
  • 1
    l, c, and r don't take arguments like that. You should use p. Apr 23, 2019 at 20:12
  • [h] has nothing to do in a longtable, as it is not a float.
    – Bernard
    Apr 23, 2019 at 20:19

1 Answer 1


Maybe you are interested in using the W{<alignment>}{<width>} column type that was recently introduced in the array package.




\begin{longtable}{W{l}{.15\textwidth-2\tabcolsep} W{l}{.7\textwidth-2\tabcolsep} W{r}{.15\textwidth-2\tabcolsep}} 
        \textbf{Symbol} & \textbf{Description} & \textbf{Units} \\ \hline


Please also keep in mind that I have also changed the widths of the columns as currently the table is still wider than the text width. This is due to the tabcolsep that is responsible for some horizontal white space on both sides of a cell. In order make the table as wide as the text width, I have used the calc package and used widths like 0.15\textwidth-2\tabcolsep}.

  • Thanks for the information. I was struggling with setting up the long table.
    – Rajath Pai
    Apr 24, 2019 at 9:17

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