hi! im new with inheritance.
can anyone tell me what to do/how to solve this error:

LNK2001: unresolved external symbol "public: __thiscall Circle::Circle(double,int,int)" (??0Circle@@QAE@NHH@Z)
cylinder.obj : (?area@Circle@@QBENXZ)
error LNK1120: 7 unresolved externals

I've already searched for it but i didn't get it..
thank you!

(I removed my codes. thanks for understanding :) )

Circle( double r = 0.0, int x = 0, int y = 0 );

Prototypes aren't enough, you'll have to define the functions too.