C# (CSharp) PayPal.PayPalAPIInterfaceService PayPalAPIInterfaceServiceService.DoExpressCheckoutPayment - 12 examples found. These are the top rated real world C# (CSharp) examples of PayPal.PayPalAPIInterfaceService.PayPalAPIInterfaceServiceService.DoExpressCheckoutPayment extracted from open source projects. You can rate examples to help us improve the quality of examples.