To make it seem like the following, I would like to add a frame box to the numbering of each section, subsection, and subsubsection.
but the following code doesn't seem to work for 'subsubsection'.
\documentclass[12pt,a4paper]{report}
\usepackage[french]{babel}
\usepackage[a4paper,margin=0.5in]{geometry}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\usepackage[Glenn]{fncychap}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\renewcommand\thesection{\fbox{\Roman{section}}}
\renewcommand\thesubsection{\fbox{\arabic{subsection}}}
\renewcommand\thesubsubsection{\fbox{\begin{english}\textit{\alph{subsubsection}}\end{english}}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document}
\chapter{}
\section{Section}
\subsection{Subsection 1}
\subsection{Subsection 2}
\subsubsection{\fbox{a} subSubsection}
\subsubsection{\fbox{b} subSubsection}
\section{section}
\subsection{subsection}
\subsubsection{\fbox{a} subsubsection}
\end{document}
subsubsection
on my system, is it not for yours?report
document class executes\setcounter{secnumdepth}{2}
, i.e., it doesn't number subsubsection-level headers automatically. Run\setcounter{secnumdepth}[3}
to get the desired outcome.