use strict;
use warnings;

for my $a (0,1) {
  for my $b (0,1) {
    for my $c (0,1) {
      print "a=$a, b=$b, c=$c\n";
      print "true1\n" if ($a and $b) or $c;
      print "true2\n" if ($a and $b) || $c;
      print "true3\n" if  $a and $b  or $c;
    }
  }
}
"test.pl" 13 lines, 265 characters
peters@ronin:~> perl test.pl
a=0, b=0, c=0
a=0, b=0, c=1
true1
true2
true3
a=0, b=1, c=0
a=0, b=1, c=1
true1
true2
true3
a=1, b=0, c=0
a=1, b=0, c=1
true1
true2
true3
a=1, b=1, c=0
true1
true2
true3
a=1, b=1, c=1
true1
true2
true3