\fontsize command not working as expected

Question

I have some tables in the middle of a document which is in written in 12pt and I'm trying to make them in 10pt. Only the tables. If I write

\begin{table}
\centering
\fontsize{10}{12}
\begin{tabular}{clcc}\hline
Variable & flag & flag & Height \\\hline
$q$ & Specific & a & 46.46\\
$c$ & \CO2 & b & 46.46
\end{tabular}
\end{table}

then only the first column gets passed into 10pt. I have tried everything and the only thing that made it work is

\begin{table}
\centering
\fontsize{10}{12}\selectfont
\begin{tabular}{clcc}\hline
Variable & flag & flag & Height \\\hline
$q$ & Specific & a & 46.46\\
$c$ & \CO2 & b & 46.46
\end{tabular}
\end{table}

This doesn't look like the correct way to do it for me. What the proper way to achieve what I want and why doesn't a simple \fontsize work?

The \selectfont is indeed required to "activate" the \fontsize macro. — Steven B. Segletes, Apr 15 '16 at 17:44
For example, see http://tex.stackexchange.com/questions/25249/how-do-i-use-a-particular-font-for-a-small-section-of-text-in-my-document — Steven B. Segletes, Apr 15 '16 at 17:48
@egreg: Really? I would have staked my life on it. I'll remove it and post another comment. Thanks! — Bernard, Apr 15 '16 at 18:14
But you might as well write \footnotesize. It is equivalent, if the document size is 12pt. — Bernard, Apr 15 '16 at 18:14
@Bernard In size12.clo you find \newcommand\footnotesize{\@setfontsize\footnotesize\@xpt\@xiipt...} — egreg, Apr 15 '16 at 18:17
I see. I confess I don't look into the files in ltxbase every day ;o) — Bernard, Apr 15 '16 at 18:20

score 1 · Accepted Answer · answered Apr 15 '16 at 18:03

Fonts in LaTeX are characterized by several attributes:

encoding
family
series
shape
size
baseline skip

For each of the attributes there is a low level command

\fontencoding
\fontfamily
\fontseries
\fontshape
\fontsize

The last command has two arguments, because it sets both the size and the baseline skip.

It would be quite inefficient if each of those command immediately did a font selection, so the system works by first setting the attributes and then applying a \selectfont command.

Higher level commands such as \itshape already do the \selectfont by themselves as well as \small or similar commands.

So your \fontsize{10}{12} declaration is incomplete: some internal parameters are set, but no particular font is chosen. You have to add \selectfont either explicitly or implicitly by means of a higher level command.

In your case, just using \footnotesize would do: when the main body font is 12pt, \footnotesize chooses a 10pt font.

It's always better using a higher level command.

I preferred using the low-level command because in case the document goes back to being 10pt (as it will someday) then the font in the table will still be the same size. Great answer, though, although I still fail to see what the \fontsize command does if you still have to use a \selectfont command. — TomCho, Apr 15 '16 at 19:03

\fontsize command not working as expected

1 Answers1