# Why does inserting a space with {} only work some of the time?

I was just trying to customize my footnotes and noticed some strange (to me, at least) behavior. Usually, if I'm inserting a one-character white space I'll simply insert a pair of empty curly braces like so {}. Trying to do this with \thefootnote, however, produced no space. Compare:

\documentclass{article}

\renewcommand{\thefootnote}{\arabic{footnote}\hspace{1em}}

\begin{document}

Some dummy text.\footnote{This one works.}

\end{document}


to

\documentclass{article}

\renewcommand{\thefootnote}{\arabic{footnote}{}}

\begin{document}

Some dummy text.\footnote{This one produces no space.}

\end{document}


Why is it that empty curly braces produce no space here? In general, when should I not expect empty braces to produce a white space? Is this an instance of some more general TeX phenomenon?

• {} doesn't produce any space. – egreg Feb 25 '14 at 21:33

{} produces no space, it just starts and ends a group (or in other contexts delimits an argument)
What you are probably thinking about is that in, say, \LaTeX is the space is ignored as terminating the macro, so never produces a space token (so does not produce space in the output), but in \LaTeX{} is the macro name is terminated by { so the character does make a space token (and so makes space in the output).
\renewcommand{\thefootnote}{\arabic{footnote} }

• Hah! A space to produce a space, why didn't I think of that! Good to know why the spaces I was inserting (which, you were right to note were all after macros which ignore the space as terminating the macro) were working even though {} doesn't insert a space. – Dennis Feb 25 '14 at 22:18