If you have been in the industry before and are looking to join a software company like M$ or others they will typically not ask for samples. If you get to the interview you will have to demonstrate in real time your skills.
It is a big red flag if a company asks for samples before hand. It usally indicates you are interviewing at non tech company or they have inferior managers whom can not weed out candidates well.
As of next Tuesday, C will be flushed in favor of COBOL. Please update your programs.