This should do it.

my($quad_1, $quad_2, $quad_3, $quad_4) = 
  split /\./, $array[0];
[download]

Of course, I'm assuming that what you mean by having the address 25.255.2.0 in @array, is that the first element of @array is the string '25.255.2.0'. That would be the case if you did something like @array = '25.255.2.0' in order to get the address into your array.

If the address is in $string, simply replace $array[0] (the first element of @array) with $string and you should be good to go.

If what you mean is that the address was split into four elements and assigned to @array, something like @array = split /\./, '25.255.2.0';, then you can either just use the array indices directly, or assign them into temporary variables, like so:

$array[0] == '25' and print "The first quadrant is 25\n";
$quad_1 = $array[0];
$quad_2 = $array[1];
$quad_3 = $array[2];
$quad_4 = $array[3]; 
$quad_1 == '25' and print "The first quadrant is still 25\n";
[download]

  dug