how to grap value after ' ? '

[eluser]nancy[/eluser]
I am using barclays payment gateway.
there i need to pass a return url as we pass in paypal
and the response is send with order id appended to the return url
for example:
i have set returnurl = https://www.example.com/barclays/success/

the payment gateway sends it as GET parameter
as https://www.example.com/barclays/success/?oid=abc00001

and i am getting this error
A PHP Error was encountered
Severity: Warning
Message: Missing argument 1 for Barclays:uccess()
Filename: controllers/barclays.php
Line Number: 154


i have a controller barclay with method success($oid)

pls help ?