Need to send data from a php page to a c# program. Please help

Which version of PHP are you using?

Permitted you are using a new enough version of PHP I would use websockets.

C#
using (var ws = new WebSocket ("ws://127.0.0.1:8000")) {
ws.OnMessage += (sender, e) => Console.WriteLine ("Reply: " + e.Data);

ws.Connect ();
ws.Send ("Send: Hello");
Console.ReadKey (true);
}

PHP
$server = new \WebSocket\Server('127.0.0.1', 8000, false); // host,port,ssl

// server settings:
$server->setCheckOrigin(true);
$server->setAllowedOrigin('foo.lh');
$server->setMaxClients(100);
$server->setMaxConnectionsPerIp(20);
$server->setMaxRequestsPerMinute(1000);

$server->registerApplication('demo', \WebSocket\Application\DemoApplication::getInstance());
$server->run();

References:
https://github.com/sta/...
https://github.com/nekudo/...