I would be inclined to approach code like that using a "table-driven" approach.

Naturally, this being Perl, we can use idiomatic techniques with hashes and regexes rather than a by-the-book C-ish implementation.

An (untested) stab at your problem might look like this:

# Keys in %rules are ! $macf, ! $syman, eq $oldMac, eq $oldSym
my %rules = (
  '1111' => 'no changes',
  '1100' => 'section C UPDATE',
  '1101' => 'section B UPDATE',
  '1110' => 'SEction E updated',

  '100.' => 'MacSEction updated',
  '101.' => 'no changes to mac',

  '01.0' => 'syman update',
  '01.1' => 'no changes to syman',

);

sub mainfunction {

  my $state = join('', map { $_ ? 1 : 0 }
    ($macf == 0), ($syman == 0), ($mac eq $oldMac), ($sym eq $oldSym) 
  );

  if ( my $rule = ( grep { $state =~ $_ } keys %rules )[0] ) {
    my $result = $rules->{$rule};
    print $result . "\n";
  }

}
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