How to make an empty curve variable?

[mahanmotamedi1991 (Mahan)]

Hello everyone,

I 'm working with Grasshopper extension in Visual Studio and to be able to define an input curve I need to make an empty curve variable as reference. But I keep getting this error that there is no constructor for Curve which can get no arguments … . can somebody help me with that?

Best,

Mahan

[Mahdiyar]

Curve boundary = null;