Horizontal alignment of text blocks

Question

I want two text blocks in a horizontal row. In the middle between them, there should be an arrow pointing from left to right.

This is what I currently have:

As you see, the arrow is not in the middle between the two text blocks. That's something I want to achieve.

Right now I'm using minipages with fixed width to achieve the result above.

\begin{minipage}{.2\textwidth}
\begin{verbatim}
X := 3
Y := Z * W
Q := X + Y
\end{verbatim}
\end{minipage}
%
\begin{minipage}{.2\textwidth}
  \centering $\Rightarrow$
\end{minipage}
%
\begin{minipage}{.2\textwidth}
\begin{verbatim}
X := 3
Y := Z * W
Q := 3 + Y
\end{verbatim}
\end{minipage}

But with that solution I would have to adjust the absolute width of the minipages until the text fits inside. That's not a clean solution though, because when I change the text size (or anything else related to the font) everything will break.

Is there a clean solution to horizontally align the two text blocks, with an arrow in the middle between them, and with adjustable whitespace between the blocks and the arrow?

Answer 1

Use \hfill:

\documentclass{article}
\begin{document}
\begin{minipage}{.2\textwidth}
\begin{verbatim}
X := 3
Y := Z * W
Q := X + Y
\end{verbatim}
\end{minipage}
\hfill $\Rightarrow$ \hfill
\begin{minipage}{.2\textwidth}
\begin{verbatim}
X := 3
Y := Z * W
Q := 3 + Y
\end{verbatim}
\end{minipage}
\end{document}

Note that the arrow seem not centered because the space not filled in minipages. For a better results you can use varwidth package instead of minipage

\documentclass{article}
\usepackage{varwidth}
\begin{document}
\hfill
\begin{varwidth}{.2\textwidth}
\begin{verbatim}
X := 3
Y := Z * W
Q := X + Y
\end{verbatim}
\end{varwidth}%
\hfill$\Rightarrow$\hfill%
\begin{varwidth}{.2\textwidth}
\begin{verbatim}
X := 3
Y := Z * W
Q := X + Y
\end{verbatim}
\end{varwidth}
\hfill
\end{document}

Using \dotfill instead of \hfill you can check visually that both block are reaally equally spaced.

Note: Be careful of remove spaces around \hfill (thanks to David to note the lack of ending %).

Answer 2

Please always post complete documents, not just fragments.

If a minipage contains tabbing it is just as wide as the widest tabbing row. Don't forget the %

\documentclass{article}

\begin{document}

\begin{minipage}{.2\textwidth}\ttfamily
\begin{tabbing}
X := 3\\
Y := Z * W\\
Q := X + Y
\end{tabbing}
\end{minipage}%
\hfill $\Rightarrow$\hfill
\begin{minipage}{.2\textwidth}\ttfamily
\begin{tabbing}
X := 3\\
Y := Z * W\\
Q := 3 + Y
\end{tabbing}
\end{minipage}

\end{document}