How to call the stored procedure with the out parameter in php

How does php call a stored procedure with the out parameter? For example, stored procedure: CREATE & nbsp; check_user (vUserName & nbsp; VARCHAR (20), vUserPWD & nbsp; VARCHAR (40), out & nbsp; vUserCount & nbsp; int & nbsp;) begin & nbsp; how does php call a stored procedure with the out parameter?
For example
Stored Procedure:
CREATE check_user (vUserName VARCHAR (20), vUserPWD VARCHAR (40), out vUserCount int)
Begin
Select COUNT (*) into vUserCount from user where user_name = vUserName and user_passward = vUserPWD;
End;

How can I call the php file?


------ Solution --------------------
CREATE check_user (vUserName VARCHAR (20), vUserPWD VARCHAR (40), out vUserCount int)
Begin
Select COUNT (*) into vUserCount from user where user_name = vUserName and user_passward = vUserPWD;
End;


Send a query ("CALL check_user ('user', 'pass', @ vUserCount )");
Send query ("SELECT @ vUserCount ");
$ Row =...-> fetch_array ();

Print_r ($ row)