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<?php $command = 1; $chksum = 2; $session_id = 3; $reply_id = 4; $command_string = 'test'; $buf = pack('SSSS', $command, $chksum, $session_id, $reply_id).$command_string; $buf = unpack('C'.(8+strlen($command_string)).'c', $buf); var_dump($buf);
Output for 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
array(12) { ["c1"]=> int(1) ["c2"]=> int(0) ["c3"]=> int(2) ["c4"]=> int(0) ["c5"]=> int(3) ["c6"]=> int(0) ["c7"]=> int(4) ["c8"]=> int(0) ["c9"]=> int(116) ["c10"]=> int(101) ["c11"]=> int(115) ["c12"]=> int(116) }

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