\documentclass{article}
\usepackage[T1]{fontenc}
\begin{document}
\def\A#1{saaa#1}
\def\Aa#1{#1saaa}
\def\Aaa#1{sa#1aa}
\def\b{bb}
\def\c a#1b#2c{one#1c#2}
\meaning A
\meaning_
\meaning%
\meaning ~
\meaning ^
\meaning *
\meaning (
\meaning \
\meaning 1
\meaning !
\meaning @
\meaning #
\meaning &
\meaning \A
\meaning \Aa
\meaning \Aaa
\meaning \b
\meaning \c
\meaning \bla
\meaning {
\meaning }
\meaning $
\end{document}