$var =~ m/a(\d+)/g and print $1;
#will now print '222' because the regex starts at
# pos($var) (which is 4)

#You can also use pos() as an lvalue
pos($var) = 0;
$var =~ m/a(\d+)/ and print $1;
# NO, doesn't print '333'
# but '111' because pos($var) wat set to 0 and so
# the regexp startsat positin 0 again