Cross reference chapter number as string

Question

I'm trying to print the chapter number of a cross referenced labelled chapter, not as an Arabic or Roman numeral, but written out as a word.

I have managed to find some information here, which advises me to use fmtcount and refcount packages: http://www.dickimaw-books.com/cgi-bin/faq.cgi?action=view&categorylabel=fmtcount#ftmrefcount

Here is what I have:

\documentclass{report}
\usepackage{fmtcount}
\usepackage{refcount}
\begin{document}
\chapter{Introduction}
\label{ch:introduction}
\newcounter{chintroduction}\setcounterref{chintroduction}{ch:introduction}

Chapter~\numberstring{chintroduction} is the introduction.

Chapter~\numberstring{chmain} is the main chapter.

Chapter~\numberstring{chconclusion} is the conclusion.

\chapter{Main}
\label{ch:main}
\newcounter{chmain}\setcounterref{chmain}{ch:main}

\chapter{Conclusion}
\label{ch:conclusion}
\newcounter{chconclusion}\setcounterref{chconclusion}{ch:conclusion}
\end{document}

I realise that in order for labels to work I have to compile twice.

What I want (as the body of the introduction chapter):

Chapter one is the introduction.

Chapter two is the main chapter.

Chapter three is the conclusion.

What I get after second compilation:

Chapter one is the introduction.

Chapter zero is the main chapter.

Chapter zero is the conclusion.

I also get the following two error messages during compilation:

! You can't use `\relax' after \the.
<recently read> \c@chmain 

l.11 Chapter~\numberstring{chmain} 
                                   is the main chapter.
? 
! You can't use `\relax' after \the.
<recently read> \c@chconclusion 

l.13 Chapter~\numberstring{chconclusion} 
                                         is the conclusion.
? 

It seems like my method works for chapter labels preceding the attempt to reference them, but not those that come after. Why doesn't this work, and how can I fix it?

Answer 1

Here is a solution

\documentclass{report}
\usepackage{fmtcount}
\usepackage{refcount}
\newcommand\mtnumberstring[1]{\numberstringnum{\getrefnumber{#1}}} 
\begin{document}
\chapter{Introduction}
\label{ch:introduction}

Chapter~\mtnumberstring{ch:introduction} is the introduction.

Chapter~\mtnumberstring{ch:main} is the main chapter.

Chapter~\mtnumberstring{ch:conclusion} is the conclusion.

\chapter{Main}
\label{ch:main}

\chapter{Conclusion}
\label{ch:conclusion}
\end{document}