Commenting in Latex

14 Comments

You probably know how to add comments in Latex using the reserved character %.

% A comment line in LaTeX

 
Many LaTeX editors provide functionality to comment/uncomment entire paragraphs of your document. However, what if you are using a basic text editor or prefer not to use a menu button?

The comment package solves this by defining the comment environment. Any content within the opening and closing statements is not displayed in the final document.

\documentclass{article}
\usepackage{blindtext, xcolor}
\usepackage{comment}

\begin{document}
\blindtext
\begin{comment}
\textcolor{red}{\blindtext}
\end{comment}
\blindtext
\end{document}

 
It is important that the opening and closing commands appear on a separate line without whitespace characters. You might get the following error otherwise:

Runaway argument?
!  File ended while scanning use of \next.

14 Comments

  2. I’ve grown quite fond of the comment environment, as it allows you to turn on and turn off the commented text. In particular, I now use it for assignments to generate the version with and without solution sets. I put the answers in section blocks like this

    \begin{answer}
...
\end{answer}

    and for the version without the solutions, I just include the line

    \excludecomment{answer}

    To be fancier, and show the answers set off in shaded boxes, I also use the color and framed packages:

    \usepackage{color}
\usepackage{framed}
\usepackage{comment}
\definecolor{shadecolor}{gray}{0.875}

    as comment allows you to, when showing the commented block, set it in any environment:

    \specialcomment{answer}{\begin{shaded}}{\end{shaded}}

    Reply

  5. Kristian Sørensen

    Yeah, it definately rocks. I use

    %\begin{comment}
Section that isn't quite done
%\end{comment}

    A lot, commenting the \begin{comment} and \end{comment} out (by adding % before them) to disable them. Easily switch on/off bits of text that way.

    Reply

    • Christian Bach

      you can also use

      \usepackage{comment}
%comment out either the first or second line
\includecomment{comment} %show comments
%\excludecomment{comment}  %do not show comments
...
\begin{comment}
Section that isn't quite done
\end{comment}

      to globally show or hide comments.

      Reply

      • Hi Christian,

        Thanks for your comment with the example. That’s a nice way to include/exclude the comments.

        Best, Tom.

  6. I tried to compile the following code and it does not seem to run. I used exactly the same code as yours.

    \documentclass[11pt]{article}
\usepackage{comment}
\begin{document}
  \begin{comment}
    Something will go wrong!
  \end{comment}
\end{document}

    Be cautious. This bug caught me 20 minutes. I have no idea what lead to this.

    All the best,

    – Linfeng

    Reply

    • tom

      Thanks for your comment. The problem is with the whitespace/tab character in front of the opening and closing statement of your comment environment. I updated the post to make this clearer.

      Thanks, Tom.

      Reply

      • Hi Tom,

        I also found out that, the problem only exists when I was trying to compile the tex file using WinEdt. I switched to Vim-Latex Suite lately and the issue no longer occur in the new setting. Quite strange.

        All the best,

        – Linfeng

      • tom

        That’s strange indeed. Anyway, it seems you found a solution that works for you. Best, Tom.

  8. Manuel Flores

    Is it possible to make a comment within another comment?
    Something like:

    \documentclass[11pt,a4paper,twoside]{article}
\usepackage{comment}
\begin{document}
\includecomment{commentA}
\includecomment{commentB}
some text
\begin{commentA}
some text
\begin{commentB}
some text
\end{commentB}
\end{commentA} 
\end{document}
    Reply

Leave a Reply