Determine the port number of a SQL instance through SQL Query

DECLARE @INSTANCENAME AS VARCHAR(20)
DECLARE @KeyString as VARCHAR(500)
SELECT @INSTANCENAME = RIGHT(@@SERVERNAME,LEN(@@SERVERNAME)-CHARINDEX('\',@@SERVERNAME))

SET @keystring = 'SOFTWARE\Microsoft\Microsoft SQL Server\' + @INSTANCENAME + '\MSSQLServer\SuperSocketNetLib\Tcp'

DECLARE @port varchar(5)

EXEC xp_regread @rootkey='HKEY_LOCAL_MACHINE',
@key=@keystring,
@value_name='TcpPort',
@value=@port OUTPUT

PRINT @port + '/' + @instancename