Scusa il ritardo ma sono un po’ impegnato!
Prova così
`
\makeatletter
\lstnewenvironment{sidebyside}{%
\global\let\lst@intname\@empty
\setbox\z@=\hbox\bgroup
\setkeys{lst}{columns=fullflexible,%
linewidth=0.45\linewidth,
breaklines=true,%
breakindent=0pt,%
boxpos=t,%
basicstyle=\small\ttfamily
}%
\lst@BeginAlsoWriteFile{\jobname.tmp}%
}{%
\lst@EndWriteFile\egroup
\par\medskip\noindent%
\begin{minipage}{0.45\linewidth}%
\hbox to\linewidth{\box\z@\hss}
\end{minipage}%
\hfill
\begin{minipage}{0.45\linewidth}%
\leavevmode \catcode`\^^M=10\relax
\small\input{\jobname.tmp}%
\end{minipage}%
\par\medskip%
}
\makeatother`
oppure questo:
`
\makeatletter
\lstnewenvironment{sidebyside}{%
\global\let\lst@intname\@empty
\setbox\z@=\hbox\bgroup
\setkeys{lst}{columns=fullflexible,%
linewidth=0.45\linewidth,
breaklines=true,%
breakindent=0pt,%
boxpos=t,%
basicstyle=\small\ttfamily
}%
\lst@BeginAlsoWriteFile{\jobname.tmp}%
}{%
\lst@EndWriteFile\egroup
\begin{flushleft}%
\begin{minipage}{0.45\linewidth}%
\hbox to\linewidth{\box\z@\hss}
\end{minipage}%
\hfill
\begin{minipage}{0.45\linewidth}
\leavevmode\catcode`\^^M=10\relax
\small\input{\jobname.tmp}%
\end{minipage}%
\end{flushleft}%
}
\makeatother`
Ciao
Andrea