[Tex/LaTex] Variables for hiding or showing text in Latex

Question

I would like to have some variables for showing or hiding text in Latex.

For example, I would like to have two versions of a document. A short version and a long version by changing a variable at the top of the latex document.

For example:

I want to set a variable long – true

and in the text I would like to use if long == true show text (long version) else if false do not show the text (short version).

Any examples?

Answer 1

\documentclass{article} 
\usepackage{lipsum}    
\newif\iflong

\begin{document}

  \longtrue   
  \iflong \lipsum[1] \else short version \fi 

  \longfalse
  \iflong \lipsum[1] \else short version \fi 
\end{document}   

With ifthen

\documentclass{article} 
\usepackage{ifthen}
\newboolean{long}   

\begin{document}

\setboolean{long}{false}   
\ifthenelse{\boolean{long}}{long version}{short version} 

\setboolean{long}{true}
\ifthenelse{\boolean{long}}{long version}{short version}  
\end{document}