Redirect root to index.php

[anarchoi]

I simply want to redirect the root of my domain name to index.php every time someone access my domain... I tryed various htaccess codes that i found on google, but none worked

http://www.mydomain.com
would redirect to
http://www.mydomain.com/index.php

and "http://www.mydomain.com/index.php" would be displayed in the URL bar of the browser

how can i do it ?

thanks