LaTeX is widely used in science and programming has become an important aspect in several areas of science, hence the need for a tool that properly displays code. This article explains how to use the standard verbatim environment as well as the package listings, which provide more advanced code-formatting features. This separate article discusses the minted
package, which performs syntax-highlighting using Python's pygmentize
library.
The default tool to display code in LaTeX is verbatim
, which generates an output in monospaced font.
\begin{verbatim}
Text enclosed inside \texttt{verbatim} environment
is printed directly
and all \LaTeX{} commands are ignored.
\end{verbatim}
Just as in the example at the introduction, all text is printed keeping line breaks and white spaces. There's a starred version of this command whose output is slightly different.
\begin{verbatim*}
Text enclosed inside \texttt{verbatim} environment
is printed directly
and all \LaTeX{} commands are ignored.
\end{verbatim*}
In this case white spaces are emphasized with a special symbol.
Verbatim-like text can also be used in a paragraph by means of the \verb
command.
In the directory \verb|C:\Windows\system32| you can find a lot of Windows
system applications.
The \verb+\ldots+ command produces \ldots
The command \verb|C:\Windows\system32|
prints the text inside the delimiters |
in verbatim format. Any character, except letters and *, can be used as delimiter. For instance \verb+\ldots+
uses +
as delimiter.
Using the lstlisting
environment from the listings
package:
\begin{lstlisting}
import numpy as np
def incmatrix(genl1,genl2):
m = len(genl1)
n = len(genl2)
M = None #to become the incidence matrix
VT = np.zeros((n*m,1), int) #dummy variable
#compute the bitwise xor matrix
M1 = bitxormatrix(genl1)
M2 = np.triu(bitxormatrix(genl2),1)
for i in range(m-1):
for j in range(i+1, m):
[r,c] = np.where(M2 == M1[i,j])
for k in range(len(r)):
VT[(i)*n + r[k]] = 1;
VT[(i)*n + c[k]] = 1;
VT[(j)*n + r[k]] = 1;
VT[(j)*n + c[k]] = 1;
if M is None:
M = np.copy(VT)
else:
M = np.concatenate((M, VT), 1)
VT = np.zeros((n*m,1), int)
return M
\end{lstlisting}
In this example, the outupt ignores all LaTeX commands and the text is printed keeping all the line breaks and white spaces typed. To use the lstlisting environment you have to add the next line to the preamble of your document:
\usepackage{listings}
Open an example of the listings package in Overleaf
Let's see a second example:
\begin{lstlisting}[language=Python]
import numpy as np
def incmatrix(genl1,genl2):
m = len(genl1)
n = len(genl2)
M = None #to become the incidence matrix
VT = np.zeros((n*m,1), int) #dummy variable
#compute the bitwise xor matrix
M1 = bitxormatrix(genl1)
M2 = np.triu(bitxormatrix(genl2),1)
for i in range(m-1):
for j in range(i+1, m):
[r,c] = np.where(M2 == M1[i,j])
for k in range(len(r)):
VT[(i)*n + r[k]] = 1;
VT[(i)*n + c[k]] = 1;
VT[(j)*n + r[k]] = 1;
VT[(j)*n + c[k]] = 1;
if M is None:
M = np.copy(VT)
else:
M = np.concatenate((M, VT), 1)
VT = np.zeros((n*m,1), int)
return M
\end{lstlisting}
The additional parameter inside brackets [language=Python]
enables code highlighting for this particular programming language (Python), special words are in boldface font and comments are italicized. See the reference guide for a complete list of supported programming languages.
Open an example of the listings package in Overleaf
Code is usually stored in a source file, therefore a command that automatically pulls code from a file becomes very handy.
The next code will be directly imported from a file
\lstinputlisting[language=Octave]{BitXorMatrix.m}
The command \lstinputlisting[language=Octave]{BitXorMatrix.m}
imports the code from the file BitXorMatrix.m, the additional parameter in between brackets enables language highlighting for the Octave programming language. If you need to import only part of the file you can specify two comma-separated parameters inside the brackets. For instance, to import the code from the line 2 to the line 12, the previous command becomes
\lstinputlisting[language=Octave, firstline=2, lastline=12]{BitXorMatrix.m}
If firstline
or lastline
is omitted, it's assumed that the values are the beginning of the file, or the bottom of the file, respectively.
Open an example of the listings package in Overleaf
Code formatting with the listing package is highly customisable. Let's see an example
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{listings}
\usepackage{xcolor}
\definecolor{codegreen}{rgb}{0,0.6,0}
\definecolor{codegray}{rgb}{0.5,0.5,0.5}
\definecolor{codepurple}{rgb}{0.58,0,0.82}
\definecolor{backcolour}{rgb}{0.95,0.95,0.92}
\lstdefinestyle{mystyle}{
backgroundcolor=\color{backcolour},
commentstyle=\color{codegreen},
keywordstyle=\color{magenta},
numberstyle=\tiny\color{codegray},
stringstyle=\color{codepurple},
basicstyle=\ttfamily\footnotesize,
breakatwhitespace=false,
breaklines=true,
captionpos=b,
keepspaces=true,
numbers=left,
numbersep=5pt,
showspaces=false,
showstringspaces=false,
showtabs=false,
tabsize=2
}
\lstset{style=mystyle}
\begin{document}
The next code will be directly imported from a file
\lstinputlisting[language=Octave]{BitXorMatrix.m}
\end{document}
As you see, the code colouring and styling greatly improves readability.
In this example the package xcolor is imported and then the command \definecolor{}{}{}
is used to define new colours in rgb format that will later be used. For more information see: using colours in LaTeX
There are essentially two commands that generate the style for this example:
\lstdefinestyle{mystyle}{...}
\lstset{style=mystyle}
Open an example of the listings package in Overleaf
Just like in floats (tables and figures), captions can be added to a listing for a more clear presentation.
\begin{lstlisting}[language=Python, caption=Python example]
import numpy as np
def incmatrix(genl1,genl2):
m = len(genl1)
n = len(genl2)
M = None #to become the incidence matrix
VT = np.zeros((n*m,1), int) #dummy variable
#compute the bitwise xor matrix
M1 = bitxormatrix(genl1)
M2 = np.triu(bitxormatrix(genl2),1)
for i in range(m-1):
for j in range(i+1, m):
[r,c] = np.where(M2 == M1[i,j])
for k in range(len(r)):
VT[(i)*n + r[k]] = 1;
VT[(i)*n + c[k]] = 1;
VT[(j)*n + r[k]] = 1;
VT[(j)*n + c[k]] = 1;
if M is None:
M = np.copy(VT)
else:
M = np.concatenate((M, VT), 1)
VT = np.zeros((n*m,1), int)
return M
\end{lstlisting}
Adding the comma-separated parameter caption=Python example
inside the brackets, enables the caption. This caption can be later used in the list of Listings.
\lstlistoflistings
Open an example of the listings package in Overleaf
supported languages (and its dialects if possible, dialects are specified in brackets and default dialects are italized):
ABAP (R/2 4.3, R/2 5.0, R/3 3.1, R/3 4.6C, R/3 6.10) | ACSL |
Ada (2005, 83, 95) | Algol (60, 68) |
Ant | Assembler (Motorola68k, x86masm) |
Awk (gnu, POSIX) | bash |
Basic (Visual) | C (ANSI, Handel, Objective, Sharp) |
C++ (ANSI, GNU, ISO, Visual) | Caml (light, Objective) |
CIL | Clean |
Cobol (1974, 1985, ibm) | Comal 80 |
command.com (WinXP) | Comsol |
csh | Delphi |
Eiffel | Elan |
erlang | Euphoria |
Fortran (77, 90, 95) | GCL |
Gnuplot | Haskell |
HTML | IDL (empty, CORBA) |
inform | Java (empty, AspectJ) |
JVMIS | ksh |
Lingo | Lisp (empty, Auto) |
Logo | make (empty, gnu) |
Mathematica (1.0, 3.0, 5.2) | Matlab |
Mercury | MetaPost |
Miranda | Mizar |
ML | Modula-2 |
MuPAD | NASTRAN |
Oberon-2 | OCL (decorative, OMG) |
Octave | Oz |
Pascal (Borland6, Standard, XSC) | Perl |
PHP | PL/I |
Plasm | PostScript |
POV | Prolog |
Promela | PSTricks |
Python | R |
Reduce | Rexx |
RSL | Ruby |
S (empty, PLUS) | SAS |
Scilab | sh |
SHELXL | Simula (67, CII, DEC, IBM) |
SPARQL | SQL |
tcl (empty, tk) | TeX (AlLaTeX, common, LaTeX, plain, primitive) |
VBScript | Verilog |
VHDL (empty, AMS) | VRML (97) |
XML | XSLT |
basicstyle=\ttfamily\small
)keywordstyle=\color{red}
)prebreak=\raisebox{0ex}[0ex][0ex]{\ensuremath{\hookleftarrow}}
)escapeinside={\%*}{*)}
)Open an example of the listings package in Overleaf
For more information see: