# Continuing example Counters in Beamer

I wonder how to get automated continuing example counters in Beamer. Below is my MWE. Thanks for your help.

\documentclass{beamer}
\usetheme{Warsaw}

\setbeamertemplate{theorem}[ams style]
\setbeamertemplate{theorems}[numbered]

\begin{document}

\begin{frame}
\begin{example}
This is a test example
\end{example}
\end{frame}

\begin{frame}
\setcounter{example}{2}
\begin{example}
Continued  previous example.
\end{example}
\end{frame}

\end{document}


UPDATE

I'm looking automated continuation of example counter like this one Continuing enumerate Counters in Beamer. Thanks

• Remove the line \setcounter{example}{2}. Everything should work fine. – A.Ellett Jul 7 '13 at 21:05
• Thanks @A.Ellett for your comment. Following your suggestion I will get Example 1.1 on frame 1 and Example 1.2 on frame 2. But I need Example 1.1 on both frames automatically. Thanks – MYaseen208 Jul 10 '13 at 15:50

Define a "continuation example" environment:

\documentclass{beamer}
\usetheme{Warsaw}

\setbeamertemplate{theorem}[ams style]
\setbeamertemplate{theorems}[numbered]
\newenvironment{example*}
{\endexample}

\begin{document}

\begin{frame}
\begin{example}
This is a test example
\end{example}
\end{frame}

\begin{frame}
\begin{example*}
Continued  previous example.
\end{example*}
\end{frame}

\begin{frame}
\begin{example*}
Continued  previous example.
\end{example*}

\begin{example}
New example.
\end{example}
\end{frame}

\end{document}


• Could you please point out why for this particular environment (example), \theexample or \value{example} works fine, but whenever we try to manipulate the example counter, e.g., \addtocounter{example}{-1}, the counter is termed as undefined. – Masroor Jul 10 '13 at 21:34
• @MMA There is no example counter and \theexample expands to \thetheorem. – egreg Jul 10 '13 at 21:46
• Indeed, if I have an example environment, followed by a theorem' environment, the later is numbered $n+1$, where, $n$ is the number of the first one. Any way to keep these independent? – Masroor Jul 10 '13 at 21:53
• You can define new theorems with \newtheorem, see section 12.4 in the documentation. – egreg Jul 10 '13 at 21:59

The following is a mild generalization of egreg's answer that allows for "continuing examples" mixed inbetween the regular flow of examples. I'm not convinced that this is a valid use-case, since continued examples will typically follow one another from one slide/frame to the next, but it may serve some purpose in a bigger context:

\documentclass{beamer}% http://ctan.org/pkg/beamer
\usetheme{Warsaw}
\setbeamertemplate{theorem}[ams style]
\setbeamertemplate{theorems}[numbered]
\makeatletter
\def\@firstoffive#1#2#3#4#5{#1}%
\newenvironment{example*}[1][\relax]
{\begingroup\ifx#1\relax% No optional argument
\else% Optional argument given
\@ifundefined{r@#1}{}{%
\protected@edef\cont@example@num{\csname r@#1\endcsname}%
\expandafter\edef\expandafter\cont@example@num\expandafter
{\expandafter\@firstoffive\cont@example@num}%%
\renewcommand{\thetheorem}{\cont@example@num}}%
\fi\addtocounter{theorem}{-1}% Revert to previous theorem count
\example}
{\endexample\endgroup}
\makeatother
\begin{document}

\begin{frame}
\begin{example}
This is a test example.
\end{example}

\begin{example*}
This one continues.
\end{example*}

\begin{example}
Another example.\label{myexample}
\end{example}
\end{frame}

\begin{frame}
\begin{example}
This is a test example.
\end{example}

\begin{example*}[myexample]
Continued previous example.
\end{example*}

\begin{example}
Another new example.
\end{example}
\end{frame}

\end{document}


The continued example environment example* now comes with an optional argument that should contain a reference to a \label set in the example that should be continued. If no argument is given, example* acts as expected and continues the previous example.

Try overlays:

\documentclass{beamer}
\usetheme{Warsaw}

\setbeamertemplate{theorem}[ams style]
\setbeamertemplate{theorems}[numbered]

\begin{document}

\begin{frame}
\only<1>{  \begin{example}
This is a test example
\end{example}
}
\only<2>{
\begin{example}
Continued  previous example.
\end{example}}
\begin{example}
Another  previous example.
\end{example}
\end{frame}
\begin{frame}
\begin{example}
Another  previous example.
\end{example}
\end{frame}
\end{document}


Only I can can't see 1.1 but 1 as you stated in the comments. So you possibly used another code?

# No. 2

Saves counter, and sets counter to the saved value. Usage: smyex is the parent while emyex is the child which has the same number, until the next use of smyex . Hope this is what you understand under automation.

\documentclass{beamer}
\usetheme{Warsaw}

\setbeamertemplate{theorem}[ams style]
\setbeamertemplate{theorems}[numbered]
\newcounter{extemp}
\newcounter{restoretemp}

\newenvironment{smyex}{\setcounter{extemp}{\theexample}\begin{example}}%
{ \end{example}}
%
\newenvironment{emyex}{%
\setcounter{restoretemp}{\thetheorem}
\setcounter{theorem}{\theextemp}
\begin{example}%
}{\end{example}\setcounter{theorem}{\therestoretemp}
}

\begin{document}

\begin{frame}
\begin{example}
This is a test example
\end{example}

\begin{smyex}
Previous example.
\end{smyex}

\begin{example}
Another  previous example.
\end{example}

\end{frame}

\begin{frame}
\begin{example}
This is a test example
\end{example}

\begin{emyex}
Continued  previous example
\end{emyex}

\begin{example}
Another  previous example.
\end{example}

\end{frame}

\end{document}
`

• This is good workaround but still not automated way. – MYaseen208 Jul 10 '13 at 16:56