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 function subnet($hosts)
 {
	$bits       = decbin($hosts) + 2; // Add 2 for Network ID and Broadcast
	$hostBits   = strlen($bits); // find how many bits it takes to represent it
	$cidr       = 32 - $hostBits; // Find slash-notation
	$binaryMask = str_repeat('1', $cidr) . str_repeat('0', $hostBits); // Subnet in binary
	$subnet     = implode('.', array_map('bindec', str_split($binaryMask, 8))); // Subnet in dotted-decimal
	return array('hosts' => $hosts, 'hostBits' => $hostBits, 'cidr' => '/' . $cidr, 'binaryMask' => $binaryMask, 'subnet' => $subnet);
 }

function subnet($hosts) { $bits = decbin($hosts) + 2; // Add 2 for Network ID and Broadcast $hostBits = strlen($bits); // find how many bits it takes to represent it $cidr = 32 - $hostBits; // Find slash-notation $binaryMask = str_repeat('1', $cidr) . str_repeat('0', $hostBits); // Subnet in binary $subnet = implode('.', array_map('bindec', str_split($binaryMask, 8))); // Subnet in dotted-decimal return array('hosts' => $hosts, 'hostBits' => $hostBits, 'cidr' => '/' . $cidr, 'binaryMask' => $binaryMask, 'subnet' => $subnet); }