Cognizant C++ Software Developer interview questions

About project, How you use Multi-threading explain, Debugging how do you do VS2012. What compilers you use. Difference between mutex, semaphore how they are different. Where can you apply synchronization techniques what will you use to do them. Storage classes in c Difference between global and external Static variable 2nd round with client: Different CPP programs were given and asked for expected ouput. cpp programs include all oops concepts, virtual, virtual destructor

Difference between drop, delete, truncate?