For a good average:
$X[0] = $a;
Well, this gives $X[0] == '', at least on 5.8 here... (And I'm pretty sure it does too on 5.6.x.. :o)
$X[1] = //; $X[2] = $^F++; $X[3] = $^F++;
So, why not just
$X[0] = $a++; $X[1] = $a++; $X[2] = $a++; $X[3] = $a++;
Duh. :o)
lg, daniel