IF you are New to the Interviews Let me tell you one thing For C interviews only c is not asked c++ is also combined or some other things sql,gtk,linux,unix will be asked so atleast know the concept of oops when you are going for c interviews
Some people when you are not able to answer C the yask ok man on which you are confortable and they may proceed but be cautious you are going for negative mark.
Before going for interview please atleast read ones kernighan and ritche book one and try to solve all exercises
after that many websites are available for Faqs but be sure of basic interviews mainly people test basics
Make sure be prepared for this like questions at hr?
How do you rate your self in C and C++ at the scale of 10?....etc