What's the shortest code to cause a stack overflow? [closed]

Answer 1

TeX:

\def~{~.}~

Results in:

! TeX capacity exceeded, sorry [input stack size=5000].
~->~
    .
~->~
    .
~->~
    .
~->~
    .
~->~
    .
~->~
    .
...
<*> \def~{~.}~

LaTeX:

\end\end

Results in:

! TeX capacity exceeded, sorry [input stack size=5000].
\end #1->\csname end#1
                      \endcsname \@checkend {#1}\expandafter \endgroup \if@e...
<*> \end\end