# How to display chapter/section counter value?

I'm building a \documentclass[...]{book} latex file. Each chapter has some sections. Each section has some exercises. The exercises are displayed on \exercise command. In the preamble I did:

\newcommand{\exercise}{
\paragraph{Exercício x}
}


How can I set x = \chapter . \section . \mycounter?

The \mycounter counter has to reset at beginning of each new section (I don't care about chapter because all exercises will be inside a section).

• \thechapter.\thesection.\themycounter? or better define \themycounter as \renecommand{\thechapter.\thesection.\arabic{mycounter}} . welcome to tex.se! – Zarko Nov 17 '18 at 19:03
• @Zarko Under normal circumstances \thesection already prints the chapter number, so \thechapter.\thesection would duplicate the chapter number. – Phelype Oleinik Nov 17 '18 at 19:09
• @PhelypeOleinik, well, you explain this in your answer. but not knowing anything about op document, it is difficult to say what is usual ... :-). – Zarko Nov 17 '18 at 19:16
• @Zarko I completely agree :-) – Phelype Oleinik Nov 17 '18 at 19:19

You have to define a counter exercise with \newcounter{exercise}, then you say that it restarts at every section with \counterwithin{exercise}{section}.

To make \thesection (which prints the value of the section) to be chapter.section.exercise you can use \thesection.\arabic{exercise} because \thesection is already defined to print chapter.section. Of course you could also use \arabic{chapter}.\arabic{section}.\arabic{exercise}, but then if any of them happened to be, for instance, with roman numbers, it would look inconsistent.

Finally, at each exercise you use \refstepcounter{exercise} to add one to it, and print \theexercise.

\documentclass{book}

\usepackage{lipsum}

\newcounter{exercise}
\counterwithin{exercise}{section}
\renewcommand\theexercise{%
\thesection.\arabic{exercise}%
}
\newcommand{\exercise}{%
\refstepcounter{exercise}%
\paragraph{Exercício~\theexercise}
}

\begin{document}