How can I calculate my Broadcast Address in PHP?

I am trying to use bitwise operators to work out the broadcast address using PHP. I am facing an issue when using the~ (NOT) operator to invert the subnet mask as it returns in string format.

// Derive from inputs normally
$ipv4        = '130.45.34.36';
$subnet_mask = '255.255.240.0';

$network = (object) [
    'ipv4'          => explode('.', $ipv4),
    'subnet_mask'   => explode('.', $subnet_mask)
];

$broadcast      = [];
$net_address    = [];

for($i = 0; $i <= count($network->ipv4) -1; $i++)
    $broadcast[$i]  = ($net_address[] = (float) $network->ipv4[$i] & (float) $network->subnet_mask[$i])
                        | ((int) ~$network->subnet_mask[$i]) +256;

printf("Network Address: %s\n", implode('.', $net_address)); // 130.45.32.0 (Expected)
printf("Broadcast Address: %s", implode('.', $broadcast));   // 386.301.288.256 (Unexpected)
Copy code

Since~$network->subnet_mask[$i] returns a string, I've tired to cast it first to an(int) which has caused the unexpected result - without this cast, I get astring + int conversion error. I assume I need a different datatype, any help appreciated. My expected Broadcast Address is:130.45.47.255.

EDIT #1: I have tried to use(float) casts, which resulted in the same output.

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