foo *bar = createFooInstance();
sayHello(bar, 10);
Thats how my simple GUI system works^^(other naming convention, but the same way).
for example if i have a struct called TFrame (the T is from Type used in Delphi....)
'Methods' of it are called like
TFrame_Free
TFrame_Create
TFrame_Paint
etc
(First parameter is always the instance)
Greets
Rackscha