Tukukkk

I want remove the space in my table of contents of section, subsection and subsubsection.

This is my code:

documentclass{book}

usepackage[utf8]{inputenc}

usepackage{imakeidx}

makeindex[columns=3, title=Alphabetical Index, intoc]



begin{document}



tableofcontents

chapter{chapter}

section{Introduction}

In this example several keywordsindex{keywords} will be 

used which are important and deserve to appear in the 

Indexindex{Index}.

 subsection{subsection}

Terms like generateindex{generate} and someindex{others} 

will also show up. Terms in the index can also be 

nested index{Index!nested}



clearpage



section{Second section}

This second sectionindex{section} may include some special 

word, and expand the ones already usedindex{keywords!used}.



printindex

end{document}

Using tocloft, these lengths are managed by cftXindent where X includes chap (for chapter), sec (for section) and subsec (for subsection):

documentclass{book}



usepackage{lipsum}

usepackage{tocloft}



setlength{cftsecindent}{0pt}% Remove indent for section

setlength{cftsubsecindent}{0pt}% Remove indent for subsection

% setlength{cftsubsubsecindent}{0pt}% Remove indent for subsubsection



begin{document}



tableofcontents



chapter{A chapter}

section{First section}lipsum[1-5]

subsection{A subsection}lipsum[6-10]

section{Second section}lipsum[11-15]



end{document}

A solution with titletoc:

 documentclass{book}

 usepackage[showframe]{geometry}

usepackage[utf8]{inputenc}

usepackage{imakeidx}

makeindex[columns=3, title=Alphabetical Index, intoc]

usepackage{titletoc}

contentsmargin{0.2pt}

titlecontents{section}

  [2.5em]

  {vspace*{baselineskip}mdseries}

  {contentslabel[thecontentslabel]{2.5em}}

  {}

{hfillthecontentspage}

titlecontents{subsection}

  [2.5em]

  {vspace*{baselineskip}mdseries}

  {contentslabel[thecontentslabel]{2.5em}}

  {}

{hfillthecontentspage}

  



begin{document}



tableofcontents

chapter{chapter}

section{Introduction}

In this example several keywordsindex{keywords} will be

used which are important and deserve to appear in the

Indexindex{Index}.

 subsection{subsection}

Terms like generateindex{generate} and someindex{others}

will also show up. Terms in the index can also be

nested index{Index!nested}



clearpage



section{Second section}

This second sectionindex{section} may include some special

word, and expand the ones already usedindex{keywords!used}.



printindex



end{document}