How to number Theorems, Lemmas... by using \newcounter with mdframed

Question

I need to show the numbering of Theorems, Lemmas,... as follows:

Theorem 3.5.2 (Theorem 2 in section 5 in chapter 3).

Fore more information, you can visit Fancy boxes for theorem, lemma, and proof with mdframed

How can I do that?

MWE

\newcounter{thm}[chapter]\setcounter{thm}{0}
\renewcommand{\thethm}{\arabic{chapter}.\arabic{thm}}
\newenvironment{thm}[2][]{%
\refstepcounter{thm}%
\ifstrempty{#1}%
{\mdfsetup{%
frametitle={%
\tikz[baseline=(current bounding box.east),outer sep=0pt]
\node[anchor=east,rectangle,fill=green!20]
{\strut Theorem~\thethm};}}
}%
{\mdfsetup{%
frametitle={%
\tikz[baseline=(current bounding box.east),outer sep=0pt]
\node[anchor=east,rectangle,fill=green!20]
{\strut Theorem~\thethm:~#1};}}%
}%
\mdfsetup{innertopmargin=10pt,linecolor=green!20,%
linewidth=3pt,topline=true,%
frametitleaboveskip=\dimexpr-\ht\strutbox\relax
}
\begin{mdframed}[]\relax%
\label{#2}}{\end{mdframed}}

Answer 1

The requested numbering scheme can be achieved using the code in the following MWE:

\documentclass{scrreprt}

\usepackage{mdframed}
\usepackage{tikz}

\newcounter{thm}[chapter]\setcounter{thm}{0}
\renewcommand{\thethm}{\arabic{chapter}.\arabic{section}.\arabic{thm}}
\newenvironment{thm}[2][]{%
\refstepcounter{thm}%
\ifstrempty{#1}%
{\mdfsetup{%
frametitle={%
\tikz[baseline=(current bounding box.east),outer sep=0pt]
\node[anchor=east,rectangle,fill=green!20]
{\strut Theorem~\thethm};}}
}%
{\mdfsetup{%
frametitle={%
\tikz[baseline=(current bounding box.east),outer sep=0pt]
\node[anchor=east,rectangle,fill=green!20]
{\strut Theorem~\thethm:~#1};}}%
}%
\mdfsetup{innertopmargin=10pt,linecolor=green!20,%
linewidth=3pt,topline=true,%
frametitleaboveskip=\dimexpr-\ht\strutbox\relax
}
\begin{mdframed}[]\relax%
\label{#2}}{\end{mdframed}}

\begin{document}

\chapter{test chapter}
\section{test section}
\begin{thm}
some content
\end{thm}

\end{document}

What I changed in comparison to the original code:

Original: \renewcommand{\thethm}{\arabic{chapter}.\arabic{thm}}

Changed: \renewcommand{\thethm}{\arabic{chapter}.\arabic{section}.\arabic{thm}}

As you can see, I have simply added \arabic{section} into the numbering scheme. Other numbering schemes can be customized accordingly.

Answer 2

I'd avoid hard-wiring the label in the definition: an explicit \label command seems preferable.

\documentclass{book}

\usepackage{tikz}
\usepackage{mdframed}

\newcounter{thm}[section]
\renewcommand{\thethm}{\thesection.\arabic{thm}}

\newenvironment{thm}[1][]
 {%
  \refstepcounter{thm}%
  \mdfsetup{%
    frametitle={%
      \tikz[baseline=(current bounding box.east),outer sep=0pt]
      \node[anchor=east,rectangle,fill=green!20]{\strut Theorem~\thethm\ifstrempty{#1}{}{:~#1}};%
    },
    innertopmargin=10pt,
    linecolor=green!20,
    linewidth=3pt,
    topline=true,
    frametitleaboveskip=\dimexpr-\ht\strutbox\relax,
  }
  \begin{mdframed}
 }
 {\end{mdframed}}

\begin{document}

\chapter{Main theorems}

\section{Arithmetic}

\begin{thm}\label{A}
$1+1=2$
\end{thm}

\begin{thm}\label{B}
$2+2=4$
\end{thm}

\section{Higher arithmetic}

\begin{thm}[J. de La Palice]\label{C}
$0+0=0$
\end{thm}

\end{document}