Get number of files in folder

Question

I am using the animate package and have the pdf files to animate in a separate folder. I need to input the number for the first and last file, but am occasionally changing the number of files I would like to animate. Is there any way to have LaTex automatically count the number of files in the folder?

Here is some example code that hopefully better explains what I am after

\documentclass{article}
\usepackage{animate}
%
\begin{document}
\animategraphics[controls]{1}{./pdfFolder/fileName_}{1}{numFiles}
\end{document} 

I would like LaTex to automatically update "numFiles" depending on the number of files in "pdfFolder".

Thank you in advance for your help!

Answer 1

Pure LaTeX: (fileName_1.pdf ... fileName_?.pdf)

\documentclass{article}
\usepackage{animate}
\usepackage{graphicx}

\newcounter{NumFiles}
%\setcounter{NumFiles}{-1} % fileName_0.pdf ... fileName_?.pdf

\newboolean{stop}
\whiledo{\NOT\boolean{stop}}{
  \stepcounter{NumFiles}
  \IfFileExists{./pdfFolder/fileName_\theNumFiles.pdf}{}{
    \addtocounter{NumFiles}{-1}
    \setboolean{stop}{true}
  }
}

\begin{document}
  \animategraphics[controls]{1}{./pdfFolder/fileName_}{1}{\theNumFiles}
\end{document}

Answer 2

Here is an approach with basic Unix commands and \write18{}, listing the contents first and using the wc -l command, saving the output into dummyvar.tex and reading that file to the \numFiles macro.

Of course, the shell-script should be much more failsafe, i.e. store it in a separate file, say countmyfiles.sh and source that file within \write18{source countmyfiles.sh} rather.

\documentclass{article}

\usepackage{animate}


\def\numFiles{-1}

\newread\numfileshandle
\begin{document}
\write18{rm -f dummyvar.tex ; ls -l pdfFolder/fileName_* | wc -l > ./dummyvar.tex}
\immediate\openin\numfileshandle=dummyvar.tex
\read\numfileshandle to \numFiles
\immediate\closein\numfileshandle

There are \numFiles Files

%\animategraphics[controls]{1}{./pdfFolder/fileName_}{1}{\numFiles}
\end{document} 

A test with 20 dummy files within my dummy folder pdfFolder yields 20 as output.

Answer 3

Christian has declined my suggestion about using the piped input feature, but I still think it may be interesting to show how it could be used in this case. Note how the argument of the \countfiles macro is pre-processed in order to permit the use of “special” characters, like _ and balanced occurences of { and }, while, at the same time, allowing macros (or, more generally, expandable control sequences) to be expanded, as it is shown below for \myDirName and \jobname.

% My standard header for TeX.SX answers:
\documentclass[a4paper]{article} % To avoid confusion, let us explicitly 
                                 % declare the paper format.

\usepackage[T1]{fontenc}         % Not always necessary, but recommended.
% End of standard header.  What follows pertains to the problem at hand.

\newcounter{numberOfFiles}

\makeatletter

% Beware: "special" characters like "_" that appear in the directory name must
% be either re-"\catcode"d or "\detokenize"d: the latter method is **much**
% simpler than the former, but it does **not** cope with filenames containing
% the "%" character, or unbalanced "{" and "}" characters, and in addition it
% requires e-TeX extensions (not at all a concern, these days!).
\newcommand*{\countfiles}[1]{%
    \begingroup
        \protected@edef\@tempa{#1}% before detokenizing, expand expandable (and 
                                  % unprotected) tokens
        % We use "\@inputcheck" for the temporary input pipe:
        \openin\@inputcheck "|ls -1 % the last character is the digit "one"
                \expandafter\detokenize\expandafter{\@tempa} % space meant
                |wc -l% the last character is the letter "ell"
                "\relax % without the "\relax", the ensuing "\ifeof" would be 
                        % prematurely expanded
        \ifeof\@inputcheck
            % An error message could be triggered here.
            \typeout{WARNING: Could not read \protect\numFiles!}%
        \else
            \endlinechar \m@ne % cf. exercise 20.18
            \readline\@inputcheck to\@tempa
            \setcounter{numberOfFiles}{\@tempa}%
        \fi
        \closein\@inputcheck % note: no "\immediate" needed for "\closein"
    \endgroup
}

\makeatother

\newcommand*{\myDirName}{some_directory}



\begin{document}

\setcounter{numberOfFiles}{-1}\countfiles{\myDirName}
There are \arabic{numberOfFiles} files in the specified directory.

\bigbreak

\setcounter{numberOfFiles}{-1}
In the current directory there are:
\begin{tabbing}
    \quad 999\=\kill
    \countfiles{\jobname.*}\>\arabic{numberOfFiles}\'
            file(s) whose basename is \texttt{\jobname};\\
    \countfiles{*.{tex,log}}\>\arabic{numberOfFiles}\'
            file(s) whose extension is either \texttt{.tex} or \texttt{.log};\\
    \countfiles{[A-Za-z]*.tex}\>\arabic{numberOfFiles}\'
            file(s) whose name consists only of letters, followed by the 
            extension \texttt{.tex}.
\end{tabbing}
That's all, folks!

\end{document}