Include Subsection Number in Section Number

Question

I would like Sections to display the subsection number,
but I feel that redefining \thesection will recursively affect \thesubsection.

Basically, we're looking to add a zero to the section number in headings and the table of contents.

Example:

What we currently get:

1.  Section 1   
1.1 Section 1, Subsection 1  
1.2 Section 1, Subsection 2  

What we're looking to get:

1.0 Section 1  
1.1 Section 1, Subsection 1  
1.2 Section 1, Subsection 2  

Additional info:

This post was a helpful start.

Answer 1

Simply changing \thesection so that it would show whatever it is you want it after the number, then redefine \thesubsection so as not to call \thesection.

\documentclass{article}
\renewcommand{\thesection}{\arabic{section}.0}
\renewcommand{\thesubsection}{\arabic{section}.\arabic{subsection}}

\begin{document}
    \tableofcontents
    \medskip
    text text
    \section{test}
    nah
    \subsection{test1}
    blah
    \subsection{test2}
    jah
\end{document}

resulting in

If you wish to fix the TOC you can use the tocloft package thus

\documentclass{article}
\usepackage{tocloft}


\renewcommand{\thesection}{\arabic{section}.0}
\renewcommand{\thesubsection}{\arabic{section}.\arabic{subsection}}
\renewcommand\cftsecnumwidth{2.5em}

\begin{document}
    \tableofcontents
    \medskip
    text text
    \section{test}
    nah
    \subsection{test1}
    blah
    \subsection{test2}
    jah
\end{document}

This would give you

Answer 2

Redefine \thesection to refer to subsection and \thesubsection to be the same as \thesection:

\documentclass{article}
\renewcommand{\thesection}{\arabic{section}.\arabic{subsection}}
\renewcommand{\thesubsection}{\thesection}

\begin{document}

\section{Section}

\subsection{First subsection}

\subsection{Second subsection}

\section{Section}

\subsection{First subsection}

\subsection{Second subsection}

\end{document}