what function to use?

$IP = "100.200.50.25"
$IP1 = ; result need to be 100
$IP2 = ; result need to be 200
$IP3 = ; result need to be 50
$IP4 = ; result need to be 25
$decIP = ($IP1*256*256*256)+($IP2*256*256)+($IP3*256)+$IP4
MsgBox(0, "Decimal IP is:", $decIP)