[Tex/LaTex] strut and strutbox

strut

The definition of a \strut in LaTeX is given in the source as:

211 \newbox\strutbox
212 \def\strut{\relax\ifmmode\copy\strutbox\else\unhcopy\strutbox\fi}

Shoudn't a \strutbox, give an empty box? AS you can see from the example below, it prints the ligature ae, if I include fixltx2e
and the ligature ff if I don't. \strut works as expected.

\documentclass[11pt]{article} 
\usepackage{fixltx2e}
\begin{document}
    \strutbox
    \texttt{\strutbox} 
    \textit{\strutbox}
\end{document}

Best Answer

You need to use \copy\strutbox to get the box. The definition \newbox\strutbox merely allocates a box number for the strutbox, then assigns that number to \strutbox using \chardef. Hence \strutbox in isolation typesets the character in the current font with the same number as the box number allocated to strutbox.

Related Solutions

[Tex/LaTex] Set \strut height

For example : #1 the height #2 the depth

\def\mystrut(#1,#2){\vrule height #1pt depth #2pt width 0pt}

example :

\documentclass{scrartcl}

\begin{document}   
  \def\mystrut(#1,#2){\vrule height #1pt depth #2pt width 0pt}    
  \fbox{\mystrut(18,10) qk}  
\end{document}

enter image description here

[Tex/LaTex] Definition of \strut explained

You can't \unhcopy an hbox in math mode, that's simple! Indeed

$\unhcopy\strutbox$

gives

! Incompatible list can't be unboxed.
<*> $\unhcopy\strutbox
                      $

The command \unhcopy is used outside of math mode because of two facts:

it starts horizontal mode;
it removes one level of boxing, avoiding "too deep" nesting.

A similar definition is that of \leavevmode:

\def\leavevmode{\unhbox\voidb@x}

where \voidb@x is a box register that should always remain void. The difference between \unhbox and \unhcopy is that the former destroys the contents of the box register, while the latter produces only a copy of it and leaves the register intact.

Among the duties of \fontsize is to provide a convenient \strut; the strut's height and depth are always 7/10 and 3/10 of the baselineskip, which is set by the second argument to \fontsize. So when a command such as \large is executed, also the strut is changed; it will restored when the group ends or another \fontsize command (possibly implicit) is executed.

(For the rest you're right.)

Note.

The register \voidb@x can be used to ensure that a box register is void, by saying \setbox\mybox=\box\voidb@x, which destroys the contents of \mybox and is more efficient than the equivalent {\setbox0=\box\mybox}.

Best Answer

Related Solutions

[Tex/LaTex] Set \strut height

[Tex/LaTex] Definition of \strut explained

Note.

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