# Remove chapter number before section number within TOC only

I have seen the answer to a similar question, but I want more control:

I have roman Chapters and arabic sections. I want the roman numeral to be hidden from the TOC, and from the TOC only (additionally, I will also remove them later from the section titles). The most important is that I need the cross chapter section references to show the chapter number.

I tried titletoc without success (although copying almost identically a command from the manual):

\documentclass[12pt, a4paper]{report}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{titlesec,titletoc}

\renewcommand{\thechapter}{\Roman{chapter}}
\newcommand{\thesectiononly}{\arabic{section}}  % Do not override \thesection.

% Large bold section titles with section number only
\titleformat{\section}{\Large\bfseries}{\thesectiononly}{24pt}{}

\titlecontents*{section}[12pt]{\bfseries}{\thesectiononly. }{}{\thecontentspage}

\begin{document}

% Here, we should see 1. First section......
\tableofcontents

\chapter{First chapter}

\section{First section}\label{sec:first-section}

First content.

\section{Second section}

Other content.

\chapter{Second chapter}

\section{section in second chapter}

Last content, referring to section~\ref{sec:first-section}. % Displayed as "I.1"

\end{document}


This compiles, but the resulting TOC is:

• How do I get the correct section numbering?
• How do I get default leading dots to the page number?

I know about tocloft, but haven't found a way to strip off chapter numbers using it.

• Please have a look at the answers to this question. Jun 2 '20 at 16:09
• Thank you. It's not exactly what I want : I still want chapters to be numbered in the TOC. Jun 2 '20 at 16:17

You only need to redefine \thesection and \p@section.

\documentclass[12pt, a4paper]{report}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{titlesec,titletoc}

\renewcommand{\thechapter}{\Roman{chapter}}
\renewcommand{\thesection}{\arabic{section}}
\makeatletter
\renewcommand{\p@section}{\thechapter.}
\makeatother

\begin{document}

% Here, we should see 1. First section......
\tableofcontents

\chapter{First chapter}

\section{First section}\label{sec:first-section}

First content.

\section{Second section}

Other content.

\chapter{Second chapter}

\section{section in second chapter}

Last content, referring to section~\ref{sec:first-section}. % Displayed as "I.1"

\end{document}

• What is \p@section ? Is it described in the Latex macros? Jun 2 '20 at 16:29
• you ca find it in source2e Jun 2 '20 at 16:34
• Incredible, here is a latex problem solved in 3 simple lines... and this has the added benefit that titlesec and titletoc packages are not needed anymore. Jun 2 '20 at 16:34
• I am being futile, but now from within a chapter, is there a way to refer to same-chapter sections without the \p@section part?... I am using the cleverref package. For example by using a new macro \localcref? Jun 3 '20 at 20:51
• @PlasmaBinturong here you are tex.stackexchange.com/questions/262652/… Jun 4 '20 at 21:22