In response to a very simplistic solution suggestion using Shell, here is a basic version of what I use. The advantage of the solution below is that it is supposed to be much faster on directories with many files (I regularly use its full-blown version on directories with tens and hundreds of thousands of files).

#!/usr/bin/perl
$ARGV[0] = '.' unless @ARGV;
for my $dir (@ARGV) {
  opendir DIR, $dir or die "$dir: $!\n";
  $file =~ m:^\.: or ++$count
    while ($file = readdir DIR);
  closedir DIR;
}
print "$count\n";
exit 0;