Latex: how to use conditional compilation

If you want to use condition to control your texts, better to use \ifthenelse.
Usage in pre-docu:
\usepackage{ifthen}
\newboolean{yourBoolVar}
\setboolean{yourBoolVar}{boolval} % boolvar=true or false

Usage in main body:
\ifthenelse {\boolean{yourBoolVar}}
{if true, go this code} {if false, go this}