$s1 = "45 20 00 00 00 03 00";
$s2 = "40 20 00 00 00 00 00";

while ((@a = $s1 =~ /(\d{2})/g) && (@b = $s2 =~ /(\d{2})/g)){
        print "found $a[0] and $b[0] !!!\n";
}

##</code><code>##

found 45 and 40 !!!
found 45 and 40 !!!
found 45 and 40 !!!
found 45 and 40 !!!
found 45 and 40 !!!
found 45 and 40 !!!
found 45 and 40 !!!
found 45 and 40 !!!
found 45 and 40 !!!
found 45 and 40 !!!
found 45 and 40 !!!
found 45 and 40 !!!
...
continues until i break