Error while compiling a Objective C code

[Gupta, Arjit (HP Labs India)]

Sir, 

I have been getting an error 
/mingw/lib/libmingw.a<main.o>:main.c:<.text+0xbd>:Undefined refrence to 
address@hidden
Collect2 :Id returned 1 exit    status

I am not able to compile a simple objective C class main the main.

Thanks, 
Arjit