Coding for Readability

# function that will check to ensure the username are
# password match and are ok
sub checkLogin {
  my ($loginname) = @_;

  open USERFILE, " $SETTINGS{'userfile'}"
                              || die "Failed to open file: $!";
  if ($^O ne "MSWin32") { flock(USERFILE, LOCK_EX); }
  while (<USERFILE>) {
    my @fields = split(/\t/,$_); # split $line, using : as delimiter 
    if (@fields[1]=~m/^$loginname$/) {
  if (@fields[2]=~m/^$password$/) {
    $matchokay='true'; # login name matches password
  }
    }
  }
  close(USERFILE);

  if ($matchokay) { return $matchokay; }
  else { return ''; }
}

Example 1: Hard-to-read code.