Use of new in C++

From: Krishna (annamrak_at_anz.com)
Date: 09/29/04 

Date: 28 Sep 2004 21:09:35 -0700

What is the differnce in these new operators

char *a = new char[21];
char *a = new char(21);

Do the type of brac matter ?.. If yes what do they signify ?..