Environment preview and \hfill command

Question

Here is a minimal code example.

\documentclass[12pt]{article}
\usepackage[active,tightpage]{preview}
\begin{document}
\begin{preview}
$a=b$
\[ b=c \]
\hfill $c=d$
\end{preview}
\end{document}

This is producing the following result.

Without preview, the following (and expected) result is produced.

Is there a way to get the second result with preview environment ?

Answer 1

Just add a \par.

\documentclass[12pt]{article}
\usepackage[active,tightpage]{preview}
\begin{document}
\begin{preview}
$a=b$
\[ b=c \]
\hfill $c=d$\par
\end{preview}
\end{document}