\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}