LaTeX forum ⇒ General ⇒ How to print out the value of \textwidth?

[fractal.generator]

Dear all,

I want to print out the value of \textwidth in the =? placeholder as follows

\newcommand*{\MARKER}%
  {\noindent\strut\vrule
   \hrulefill~half textwidth =? cm~\hrulefill\vrule
   \hrulefill~half textwidth =? cm~\hrulefill\vrule
    \marginpar{\strut\vrule\hrulefill~marginpar~\hrulefill\vrule}}

Please help me.


Thank you in advance.

regards,

Hayashi

[Juanjo]

\the\textwidth

[fractal.generator]

\the\textwidth

Mr. Juanjo,
Thanks for replying.

Is it possible to convert the unit from pt to cm?

Thanks in advance.

[Stefan Kottwitz]

Hi,

as I don't know a more direct way I've made a calculation and manipulated it's output, here's a demonstration example:

\documentclass[a4paper,10pt]{article}
\setlength{\textwidth}{14cm}
\newlength\textwidthcm
\textwidthcm=.03514598035146\textwidth
\begin{document}
{\catcode`p=12 \catcode`t=12 \gdef\cm#1pt{#1cm}}
\begin{tabular}{ll}
textwidth in pt: \the\textwidth \\
textwidth in cm: \expandafter\cm\the\textwidthcm
\end{tabular}
\end{document}

Output is 13.998, so there may be a small rounding error, I just used 72.27pt=1in and 1in=2.54cm for the calculation.
But there are packages that are capable of floating point operations.

Stefan

[Juanjo]

With the help of the \catcode trick given by Stephan_K and the fp package, it is possible to define macros to convert from one unit to another:

\documentclass[a4paper]{article}
\usepackage{fp}

\newlength{\TOarg} \newlength{\TOunit}
{\catcode`p=12 \catcode`t=12 \gdef\TOnum#1pt{#1}}
\newcommand\TOop[2]{\setlength{\TOarg}{#2}%
   \FPdiv\TOres{\expandafter\TOnum\the\TOarg}{\expandafter\TOnum\the\TOunit}%
   \FPround\TOres\TOres{#1}}
\newcommand{\TOspace}{\ } 
\newcommand\TOpt[2][2]{\setlength{\TOunit}{1pt}\TOop{#1}{#2}\TOres\TOspace pt}
\newcommand\TOin[2][2]{\setlength{\TOunit}{1in}\TOop{#1}{#2}\TOres\TOspace in}
\newcommand\TOcm[2][2]{\setlength{\TOunit}{1cm}\TOop{#1}{#2}\TOres\TOspace cm}
\newcommand\TOmm[2][2]{\setlength{\TOunit}{1mm}\TOop{#1}{#2}\TOres\TOspace mm}
\newcommand\TOem[2][2]{\setlength{\TOunit}{1em}\TOop{#1}{#2}\TOres\TOspace em}

\begin{document}
The width of this document is \TOpt[0]{\textwidth}, that is, \TOcm{\textwidth}, whereas the height is \TOcm[3]{\textheight}, i.e. \TOin{\textheight}. Here we have some equivalences between different units:

\begin{center}
   \renewcommand{\arraystretch}{1.5}
   \begin{tabular}{r*{4}{@{\ =\ }r}}
      1pt & \TOpt[0]{1pt} & \TOin[3]{1pt} & \TOcm{1pt} & \TOmm{1pt}  \\ 
      1in & \TOpt{1in} & \TOin[0]{1in} & \TOcm{1in} & \TOmm[1]{1in}  \\
      1cm & \TOpt{1cm} & \TOin[3]{1cm} & \TOcm[0]{1cm} & \TOmm[0]{1cm}  \\
      1mm & \TOpt{1mm} & \TOin[3]{1mm} & \TOcm{1mm} & \TOmm[0]{1mm}  
   \end{tabular}
\end{center}

The em unit depends on which font is active:
\begin{itemize}
   \item 1 cm = \TOem{1cm}, 1 em = \TOcm{1em}
   \item {\bfseries 1 cm = \TOem{1cm}, 1 em = \TOcm{1em}}
   \item {\bfseries \large 1 cm = \TOem{1cm}, 1 em = \TOcm{1em}}
   \item {\ttfamily 1 cm = \TOem{1cm}, 1 em = \TOcm{1em}}
\end{itemize}
\end{document}

The optional argument of TOpt, TOcm and like fixes the number of decimal digits shown (2 by default). These macros first convert their mandatory argument to pt (done automatically by TeX) and then the conversion to the corresponding unit.
From the above code, it is easy to add macros for conversion to pc, ex, bp and so on.

[Stefan Kottwitz]

Hi Juanjo,

you've given a very good demonstration!
Btw. I've read the catcode trick in the TeXbook Appendix D: Dirty Tricks.

Stefan

[fractal.generator]

To Stefen and Juanjo,

thanks for replying.


I am trying to diggest the codes



Hayashi

[Juanjo]

Hi Juanjo,

you've given a very good demonstration!
Btw. I've read the catcode trick in the TeXbook Appendix D: Dirty Tricks.

Stefan

Well, not so good, since I've reinvented the wheel! I've found that the layouts package defines the commands \printinunitsof and \prntlen. The latter prints the value of a length in the units specified by the former. So, for example, after loading layouts, the code

\printinunitsof{cm}\prntlen{\textwidth} \prntlen{\textheight}

prints the value of \textwidth and \textheight expressed in cm. Reading layouts.sty, one sees that conversion is internally done by multiplication by a suitable factor (without the help of fp). The code there uses the internal LaTeX macro \strip@pt, similar to (but much more elaborated than) \TOnum in my code. In fact, with the help of this macro, my code can be simplified: \TOnum is unnecessary and \TOop can be given by

\makeatletter
\newcommand\TOop[2]{\setlength{\TOarg}{#2}\FPdiv\TOres{\strip@pt\TOarg}{\strip@pt\TOunit}\FPround\TOres\TOres{#1}}
\makeatother

[fractal.generator]

Dear all,

By accident, I found a package about this topic:
http://www.ctan.org/tex-archive/help/Catalogue/entries/printlen.html


regards,


Hayashi