This was an campus interview. First round was written testing aptitude and C skills.2 subsequent rounds were interviews testing logic, problem solving and programming skills. Be very thorough with corner cases in C like bit wise operators, extensive looping, tracing output of multiple nested loops, pointers, etc for the written round. Be thorough with logic and problem solving abilities for the interviews - practice general and computer science problems several days before the interview. Practice coding these solutions - OOPS is best in C++, recursions, loops. Practice explaining your code to others. Avoid monolithic blocks of code in C, static and global variables at any cost.