Using bold/italic text inside listings?

Question

How can I use bold text inside a code listing? I wanted to make some parts of the code bold.

Answer 1

As per Mico's answer, there is no boldfaced monospaced font in the Computer Modern font family, so you need to use a font that has bold monospaced font. Below is an example using listings that make the keywords bold using the pxfonts. Here is a comparison of the results without and with the \usepackage{pxfonts}:

\documentclass[border=2pt]{standalone}
\usepackage{listings}
\usepackage{pxfonts}
\lstset{language=C,
    basicstyle=\ttfamily,
    keywordstyle=\bfseries,
    showstringspaces=false,
    morekeywords={include, printf}
}
\begin{document}
\begin{lstlisting}
    /* Prints Hello World */
#include <stdio.h>

int main(void) {
   printf("Hello World!");
   return 0;
}

\end{lstlisting}
\end{document}

---

Alternate Solution:

You could also use the the courier font form ttfamily with bfseries or how to enable bold in fixed width font:

\documentclass[border=2pt]{standalone}
\usepackage{listings}
\lstset{language=C,
    basicstyle=\ttfamily,
    keywordstyle=\bfseries,
    showstringspaces=false,
    morekeywords={include, printf}
}
\begin{document}
\begin{lstlisting}
    /* Prints Hello World */
#include <stdio.h>

int main(void) {
   printf("Hello World!");
   return 0;
}

\end{lstlisting}
\hrule
\renewcommand{\ttdefault}{pcr}
\begin{lstlisting}
    /* Prints Hello World */
#include <stdio.h>

int main(void) {
   printf("Hello World!");
   return 0;
}

\end{lstlisting}
\end{document}

Answer 2

As you must have already discovered, there is no boldfaced monospaced font in the Computer Modern font family. (Computer Modern is what's loaded by default.) To get the option of highlighting part of your code in a boldfaced font, you must switch to a different font family.

• One way to do this is to add the command \usepackage[scaled=1.04]{couriers} to the preamble of your document; doing so will tell (La)TeX to use the Courier monospaced font instead of the Computer-Modern (CM) variety. The ordinary and boldfaced versions of Courier look very different from CM mono, which is presumably what you want. The downside of using Courier is that it's set very loosely, i.e., you can't squeeze as many words into a line as you could with CM mono.

• A fairly unobtrusive option -- in the sense that the main text and math fonts are virtually indistinguishable from Computer Modern, while having access to a monospaced font that's more compact than Courier -- would be to use the Latin Modern font family, loaded with the command \usepackage{lmodern}. While this font family does have a boldface-monospaced font, it is not all that bold(faced) and thus may not meet your needs.

• Assuming you're willing to depart from the Computer/Latin Modern font family entirely, some good options for font families could be selected with either one of the following two commands: \usepackage{pxfonts} (a Palatino font) or \usepackage{txfonts} (a Times Roman font). Note that the (variable-spaced) text fonts will look very different, but the creator of these two font families gave them each the same style of monospaced text.

  • The mathptmx package, which gives you still another option for Times New Roman, does not feature a boldfaced monospaced font and hence won't do the job for you.

  • Update Jan 2019: In the meantime, i.e., since I wrote the original version of this answer back in 2011, the txfonts and pxfonts font packages have been superseded (if not entirely replaced) by newtxtext/newtxmath on the one hand and newpxtext/newpxmath on the other. By all means, if you've used the txfonts and/or pxfonts packages in the path, do consider switching to either newtxtext/newtxmath or newpxtext/newpxmath. What hasn't changed is that newtxtext and newpxtext share the same monospaced font -- both medium ("normal") and bold weight.

The following MWE serves to illustrate the effects of choosing among these options:

\documentclass{article}
%% Uncomment one (and only one) of the following four \usepackage commands:
%% \usepackage[scaled=1.04]{couriers}
\usepackage{lmodern}
%%\usepackage{pxfonts}  % Palatino font
%%\usepackage{txfonts}  % Times font

\begin{document}
%Monospaced font:
\texttt{The quick brown fox jumps over the lazy dog.}

%Monospaced font with some boldfaced words:
\texttt{The quick brown \textbf{fox} jumps over the \textbf{lazy} dog.}
\end{document}

Courier mono generates this text:

Latin Modern mono looks like this (note the rather minor difference between non-bold and bold):

Both the pxfonts and txfonts samples look like this:

Answer 3

You can use lstlisting with mathescape set to true, and then use \textbf inside maths mode.

\begin{lstlisting}[mathescape=true]
    $\textbf{Hello}$
    Hello
\end{lstlisting}

Note that the font does change a bit, and you would have to do this for every word you want to make bold. But it is an alternative, and it also works for italics and other text commands you might want to use.

Answer 4

you need a typewriter font which supports bold characters, eg:

\usepackage[scale=0.9]{beramono}

and inside the listing you can use the escape character. You'l lfind some examples in the documentation, run texdoc listings

Answer 5

I can't remember where I came across the following definition to use a boldface typewriter font with Computer Modern:

% Declare bold typewriter font with Computer Modern
\DeclareFontShape{OT1}{cmtt}{bx}{n}{<5><6><7><8><9><10><10.95><12><14.4><17.28><20.74><24.88>cmttb10}{}

Then:

\usepackage{listings}
\lstloadlanguages{Matlab}
\lstset{
  basicstyle=\scriptsize\upshape\ttfamily,
  keywordstyle=\color{blue}\bfseries,
  % etc.
}

Result:

I'm not an expert in fonts in LaTeX so I'm not entirely sure what the DeclareFontShape command does behind the scenes but I like the result.

Answer 6

The listings package might suffice.

Start with:

\usepackage{listings}

...

\lstset{morekeywords={example,foo,bar}}

...

\begin[language=C]{lstlisting}
   YOUR_CODE_HERE
\end{lstlisting}

The package allows you to define your own language definition (\lstdefinelanguage), and you get some fine-grained control about how the language is presented, so you get some re-usability of your setup (i.e., preferable over manually setting your keywords bold).