# Labeling exercises produced with tcolorbox

I produce exercises, in book environment, chapter by chapter, using the doc in the last version of tcolorbox. In this version, the labels are automatically produced (with the command label={exercise@\thetcbcounter}). I want to make my own labels, like in the previous version, by the same way as the command label={exe:#2}, where #2 is the name of the label what I want to define. How can I do this ?

I give an example of a file with the data in the doc, and I use the command

The solution of the exercise \ref{exercise@1.1} is in the page \pageref{solution@1.1}

so I want to recall the labels (found in the .aux file !) exercise@1.1 and solution@1.1 by the labels exercise:mylabel and solution:mylabel, respectively.

\documentclass{book}

\usepackage[most]{tcolorbox}
\tcbuselibrary{skins,breakable}

\usepackage{polyglossia}
\setmainlanguage{english}
\usepackage{fontspec}
\setmainfont{Times New Roman}
\setsansfont{Arial}
\setmonofont{Courier New}

\tcbuselibrary{skins,xparse}
\NewTColorBox[auto counter,number within=chapter]{exercise}{+O{}}{%
enhanced,colframe=green!20!black,colback=yellow!10!white,coltitle=green!40!black,
fonttitle=\bfseries,
underlay={\begin{tcbclipinterior}
(interior.north west) circle (2cm);
\draw[help lines,step=5mm,yellow!80!black,shift={(interior.north west)}]
(interior.south west) grid (interior.north east);
\end{tcbclipinterior}},
title={Exercise~ \thetcbcounter:},
label={exercise@\thetcbcounter},
after upper={\par\hfill\textcolor{green!40!black}%
{\itshape Solution on page~\pageref{solution@\thetcbcounter}}},
lowerbox=ignored,
savelowerto=solutions/exercise-\thetcbcounter.tex,
record={\string\solution{\thetcbcounter}{solutions/exercise-\thetcbcounter.tex}},
#1
}
\NewTotalTColorBox{\solution}{mm}{%
enhanced,colframe=red!20!black,colback=yellow!10!white,coltitle=red!40!black,
fonttitle=\bfseries,
underlay={\begin{tcbclipinterior}
(interior.north west) circle (2cm);
\draw[help lines,step=5mm,yellow!80!black,shift={(interior.north west)}]
(interior.south west) grid (interior.north east);
\end{tcbclipinterior}},
title={Solution of Exercise~\ref{exercise@#1} on page~\pageref{exercise@#1}:},
phantomlabel={solution@#1},
attach title to upper=\par,
}{\input{#2}}

\tcbset{no solution/.style={no recording,after upper=}}

\begin{document}
\chapter{The first chapter}

\tcbstartrecording
\begin{exercise}
Compute the derivative of the following function:
\begin{equation*}
f(x)=\sin((\sin x)^2)
\end{equation*}
\tcblower
The derivative is:
\begin{align*}
f’(x) &= \left( \sin((\sin x)^2) \right)’
=\cos((\sin x)^2) 2\sin x \cos x.
\end{align*}
\end{exercise}
\vspace*{1cm}
The solution of the exercise \ref{exercise@1.1} is in the page \pageref{solution@1.1}
\vspace*{1cm}
\tcbstoprecording
\tcbinputrecords

\end{document}


which gives after compiling with XeLatex:

Following code adds a mandatory argument to exercise. This mandatory argument is the label which will be added to exercise:... and solution:....

The introduction of this label implied to change label, after upper and record option definitions in exercise tcolorbox. Also previous #1 has been changed to #2.

In solution box there are no new arguments but changes in title and phantomlabel.

\documentclass{book}

\usepackage[most]{tcolorbox}
\tcbuselibrary{skins,breakable}

\usepackage{polyglossia}
\setmainlanguage{english}
\usepackage{fontspec}
\setmainfont{Times New Roman}
\setsansfont{Arial}
\setmonofont{Courier New}

\tcbuselibrary{skins,xparse}

\NewTColorBox[auto counter,number within=chapter]{exercise}{m+O{}}{%
enhanced,
colframe=green!20!black,
colback=yellow!10!white,
coltitle=green!40!black,
fonttitle=\bfseries,
underlay={\begin{tcbclipinterior}
(interior.north west) circle (2cm);
\draw[help lines,step=5mm,yellow!80!black,shift={(interior.north west)}]
(interior.south west) grid (interior.north east);
\end{tcbclipinterior}},
title={Exercise~ \thetcbcounter:},
label={exercise:#1},
after upper={\par\hfill\textcolor{green!40!black}%
{\itshape Solution on page~\pageref{solution:#1}}},
lowerbox=ignored,
savelowerto=solutions/exercise-\thetcbcounter.tex,
record={\string\solution{#1}{solutions/exercise-\thetcbcounter.tex}},
#2
}

\NewTotalTColorBox{\solution}{mm}{%
enhanced,
colframe=red!20!black,
colback=yellow!10!white,
coltitle=red!40!black,
fonttitle=\bfseries,
underlay={\begin{tcbclipinterior}
(interior.north west) circle (2cm);
\draw[help lines,step=5mm,yellow!80!black,shift={(interior.north west)}]
(interior.south west) grid (interior.north east);
\end{tcbclipinterior}},
title={Solution of Exercise~\ref{exercise:#1} on page~\pageref{exercise:#1}:},
phantomlabel={solution:#1},
attach title to upper=\par,
}{\input{#2}}

\tcbset{no solution/.style={no recording,after upper=}}

\begin{document}
\chapter{The first chapter}

\tcbstartrecording
\begin{exercise}{Ex1}[coltitle=cyan!80!black]
Compute the derivative of the following function:
\begin{equation*}
f(x)=\sin((\sin x)^2)
\end{equation*}
\tcblower
The derivative is:
\begin{align*}
f’(x) &= \left( \sin((\sin x)^2) \right)’
=\cos((\sin x)^2) 2\sin x \cos x.
\end{align*}
\end{exercise}
\vspace*{1cm}
The solution of the exercise \ref{exercise:Ex1} is in the page \pageref{solution:Ex1}
\vspace*{1cm}
\tcbstoprecording
\tcbinputrecords

\end{document}


The result and auxiliary files don't change, only the contents in aux file will show new label syntax and values.

• Your works are excellent. Best regards. Jan 23, 2017 at 11:50
• I published another question, related to this one, and your help is wellcome. Would you see this link please tex.stackexchange.com/questions/350028/… Jan 23, 2017 at 13:52