Your regex does match your sample string! (But not in the way you want.) A very good reason to use a module.

A Simple fix is:

use strict;
use warnings;
use English;
my $html = '<c:t="AD2343"/><c:p>65677676</c:p>';
$html =~ m{<c:.*/>}; 
print $MATCH, "\n";
[download]