Commenting out large sections

Question

So to "comment out" a line, I need to insert a % at the beginning of the line (so that line will not be compiled).

Is there way to comment out a large section without having to manually putting a % in front of each line?

Answer 1

You can use \iffalse ... \fi to make (La)TeX not compile everything between it. However, this might not work properly if you have unmatched \ifxxx ... \fi pairs inside them or do something else special with if-switches. It should be fine for normal user text.

There is also the comment package which gives you the comment environment which ignores everything in it verbatim. It allows you to define own environments and to switch them on and off.

Answer 2

There are other ways to solve this problem than via (La)TeX.

• You can use your editor's capabilities for commenting to comment out large sections. For instance, in Emacs C-c ; comments (or uncomments) the region (see e.g. http://www.gnu.org/software/auctex/manual/auctex/Commenting.html#Commenting for details).
• You can use version control so that you may delete large sections without being afraid to lose them.

Something that is good about either of these solutions is that they are independent of particular LaTeX packages and code.

Answer 3

Another option is the comment package, which, like verbatim provides a comment environment, but offers the option to define arbitrary "throw away" environments that can selectively be enabled or disabled:

\documentclass{article}
\usepackage{comment}

% uncomment to include stuff in standard comment-environment
%\includecomment{comment}

% define a mysection env which content is excluded
\excludecomment{mysection}

\begin{document}
    This text will be displayed
\begin{comment}
    This text will only be displayed, if \includecomment{comment} was given
\end{comment}
\begin{mysection}
    This text will only be displayed, if \includecomemnt{mysection} was given
\end{mysection}
\end{document}

Additionally, the package provides some simple hooks into the defined environments. Instead of \includecomment{mysection} one could also use \specialcomment{mysection}{<before code>}{<after code>} to enable some comment section:

% typeset stuff in mycomment with gray text
\specialcomment{mysection}{\begingroup\color{gray}}{\endgroup}

Answer 4

The verbatim package provides a comment environment:

\documentclass{article}
\usepackage{verbatim}
\begin{document}
    This text will be displayed
\begin{comment}
    This text will not be displayed.
\end{comment}
\end{document}

The Not So Short Introduction to LaTeX2e mentions this option on page 6 and remarks: "Note that this won’t work inside complex environments, like math for example."

Answer 5

You can use \iffalse:

\iffalse
One morning, as Gregor Samsa was waking up from anxious dreams, he discovered
that in his bed he had been changed into a monstrous verminous bug. He lay on
his armour-hard back and saw, as he lifted his head up a little, his brown,
arched abdomen divided up into rigid bow-like sections.
\fi

Of course, this has to align with other syntactical TeX structures in you document whereas you can use % much more freely. The good news is that you can introduce your own switch to make this optional:

\newif\ifdraft
\drafttrue % or \draftfalse

\ifdraft
<only shown in draft mode>
\else 
<only shown in non-draft mode>
\fi

The \else part is optional and you could use \ifdraft ... \fi if you don't need it.