\thepage counter does not always work perfectly

Question

I have a small problem that I can not solve, and I do not understand the cause.

\thepage counter is sometimes one page earlier than the actual page where it is invoked

I think it is because the text is formatted before being added to the output.

Here is a Minimal Working Example.

\documentclass[9pt]{extbook}
\usepackage[TS1,T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{ebgaramond}
\usepackage[french]{babel}
\usepackage{geometry}
\geometry{
    right=1.2cm,
    left=1.8cm,
    top=1.8cm,
    bottom=1cm,
    paperwidth=110mm,
    paperheight=178mm
}
\newcommand\titre{%
\vspace{1em}%
{\centering%
AMAZING POEM\par%
}%
}
\begin{document}
\titre{}
\begingroup
\obeylines
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
~
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
~
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\endgroup
\titre{}
\begingroup
\obeylines
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
~
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
~
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\endgroup
\titre{}
\begingroup
\obeylines
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
~
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
~
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\endgroup
\titre{}
\begingroup
\obeylines
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
~
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
~
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\thepage
I'm an amazing poem
\endgroup
\end{document}

You can see that at the top of pages 2, 3 and 4, \thepage shows 1, 2 and 3, instead of 2, 3 and 4.

It's even worse when you use \\ instead of obeylines :

\documentclass[9pt]{extbook}
\usepackage[TS1,T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{ebgaramond}
\usepackage[french]{babel}
\usepackage{geometry}
\geometry{
    right=1.2cm,
    left=1.8cm,
    top=1.8cm,
    bottom=1cm,
    paperwidth=110mm,
    paperheight=178mm
}
\newcommand\titre{%
\vspace{1em}%
{\centering%
AMAZING POEM\par%
}%
}
\begin{document}
\titre{}
\begingroup
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
~\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
~\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\endgroup
\titre{}
\begingroup
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
~\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
~\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\titre{}
\begingroup
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
~\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
~\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\endgroup
\titre{}
\begingroup
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
~\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
~\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\thepage\
I'm an amazing poem\
\endgroup
\end{document}

I thank in advance the intelligent people who could explain me the reason of this problem.

Great thanks!

EDIT

Even with \label and \pageref, the problem is still here.

For example:

\documentclass[9pt]{extbook}
%pdfLaTeX
\usepackage[TS1,T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{ebgaramond}
\usepackage[french]{babel}
\usepackage{geometry}
\geometry{
    right=1.2cm,
    left=1.8cm,
    top=1.8cm,
    bottom=1cm,
    paperwidth=110mm,
    paperheight=178mm
}
\newcommand\titre{%
\vspace{1em}%
{\centering%
AMAZING POEM\par%
}%
}
\newcounter{nbrefpage}
\setcounter{nbrefpage}{0}
\newcommand\afficherpage{%
    \stepcounter{nbrefpage}%
    \def\tmpnbrefpage{\arabic{nbrefpage}testpage}%
    \label{\tmpnbrefpage}%
    \pageref{\tmpnbrefpage}%
}
\begin{document}
\titre{}
\begingroup
\obeylines
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\endgroup
\titre{}
\begingroup
\obeylines
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\endgroup
\titre{}
\begingroup
\obeylines
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\endgroup
\titre{}
\begingroup
\obeylines
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\endgroup
\end{document}

And the result (after 2 compilations of course) is the same:

In the .aux file, we see:

\newlabel{16testpage}{{}{1}}

instead of

\newlabel{16testpage}{{}{2}}

that is expected, you can only use \thepage where the page is known, eg in head and foot of a page style. use \label ad \pageref to refer to page in the body — David Carlisle, Jul 30 '22 at 13:44
Thanks for your answer! But, when I use \label and \pageref, I have the same problem. I don't understand why. — Pierre Dufays, Jul 30 '22 at 13:46
See also https://tex.stackexchange.com/questions/196033/how-do-i-test-for-a-new-page — John Kormylo, Jul 30 '22 at 23:48

score 2 · Accepted Answer · answered Jul 30 '22 at 13:51

You were allowing a page break between the \label and printing the number,adding a box keeps them together

\documentclass[9pt]{extbook}
%pdfLaTeX
\usepackage[TS1,T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{ebgaramond}
\usepackage[french]{babel}
\usepackage{geometry}
\geometry{
    right=1.2cm,
    left=1.8cm,
    top=1.8cm,
    bottom=1cm,
    paperwidth=110mm,
    paperheight=178mm
}
\newcommand\titre{%
\vspace{1em}%
{\centering%
AMAZING POEM\par%
}%
}
\newcounter{nbrefpage}
\setcounter{nbrefpage}{0}
\newcommand\afficherpage{%
    \stepcounter{nbrefpage}%
    \def\tmpnbrefpage{\arabic{nbrefpage}testpage}%
    \mbox{\label{\tmpnbrefpage}%
    \pageref{\tmpnbrefpage}}%
}
\begin{document}
\titre{}
\begingroup
\obeylines
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\endgroup
\titre{}
\begingroup
\obeylines
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\endgroup
\titre{}
\begingroup
\obeylines
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\endgroup
\titre{}
\begingroup
\obeylines
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
~
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\afficherpage
I'm an amazing poem
\endgroup
\end{document}

David Carlisle, I am amazed! Thank you so much! But, I don't understand why "holding together" the label and the display of the labelpage, brings a different result. — Pierre Dufays, Jul 30 '22 at 13:57
I mean: why "pageref" changes the "label" in the ".aux"? "pageref" just gets the value displayed in the ".aux". Why, with an "mbox", does "label" change its value...? — Pierre Dufays, Jul 30 '22 at 14:01
I notice that it is enough to set \mbox{\label{...}} to obtain the good reference of page. — Pierre Dufays, Jul 30 '22 at 14:03
@PierreDufays yes but that requires more implementation details to see why it works, but the version I used would work for any implemenentation of \pageref as boxes never break — David Carlisle, Jul 30 '22 at 14:59
@DavidCarliste yes I understand. But could you give me a reference, or a book, or a section of a book, which explains that aspect of LaTeX? It would be very interesting. — Pierre Dufays, Aug 01 '22 at 08:24

\thepage counter does not always work perfectly

1 Answers1