[Tex/LaTex] Get width of a given text as length

calculationslengths

Is there a TeX command that returns the width of a given text as length value, so that I can use the result directly as a length argument of another command?

I mean, I would like to have a command \getWidth{my text} and want to use the result directly as the first argument of \parbox:

\parbox{\getWidth{my text}}{my foo\\bar text}

Best Answer

Use the calc package (\usepackage{calc}):

\parbox{\widthof{my text}}{...}

Related Solutions

[Tex/LaTex] Getting length as number

You can remove the pt unit from the length using \strip@pt as shown below. I you want the number in cm you would have to convert it by yourself.

\documentclass{article}

\makeatletter
\newcommand*{\getlength}[1]{\strip@pt#1}
% Or rounded back to `cm` (there will be some rounding errors!)
%\newcommand*{\getlength}[1]{\strip@pt\dimexpr0.035146\dimexpr#1\relax\relax}

\makeatother

\begin{document}

Test: \getlength{\textwidth}  % Result: 345

\end{document}

Another alternative which is more flexible and also allows you to store the resulting number in a macro is to use pgfmath (pgf package). It also allows you to easily convert the number to cm:

\documentclass{article}

\usepackage{pgf}
\newcommand*{\getlength}[2]{%
   \pgfmathsetmacro#1{#2}%  Result in `pt`
   % Or:
   %\pgfmathsetmacro#1{0.0351459804*#2}%  Result in `cm`
}

\begin{document}

\getlength{\myNum}{\textwidth}

Test: \myNum % Result: 345.0

\end{document}

There is also the round( ) function for pgfmath which allows you to round the number, e.g. to two fractional digits. The trick is to multiple it with 100 before the rounding and divide it afterwards by 100.

\documentclass{article}

\usepackage{pgf}
\newcommand*{\getlength}[2]{%
   % Convert to `cm` and round to two fractional digits:
   \pgfmathsetmacro#1{round(3.51459804*#2)/100.0}%
}

\begin{document}

\setlength{\textwidth}{2.123cm}
\getlength{\myNum}{\textwidth}

Test: \myNum% Gives 2.12

\setlength{\textwidth}{2cm}
\getlength{\myNum}{\textwidth}

Test: \myNum% Gives 2.0

\end{document}

The fractional part (like .0) can be avoided by using \pgfmathtruncatemacro instead of \pgfmathsetmacro, but I don't think you need that.

[Tex/LaTex] How to use \widthof as parameter to \kern

\kern is a TeX primitive which awaits a dimension expression, while \widthof is a calc package function which only works in \setlength and friends. It requires internal box assignments, which are not allowed in a normal dimension expression. You can't therefore use \widthof and other things like this at positions where TeX dimension expressions are awaited. You need to use \setlength first to assign the value to a length register and then use this register, as you did.

Best Answer

Related Solutions

[Tex/LaTex] Getting length as number

[Tex/LaTex] How to use \widthof as parameter to \kern

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