use File::Find::Rule;

my $cnt = find(
  file     =>
  name     => "*.txt",
  maxdepth => 1,
  in       => "/home/a"
);

##</code><code>##

my $cnt = () = glob "/home/a/*.txt";

##</code><code>##

opendir( my $d, "/home/a" ) or die "ack: $!";
my $cnt = grep { -f and /\.txt$/ } readdir $d;