How can you tell what shell you are running on UNIX system?-placement C++ Interview Questions and Answers

How can you tell what shell you are running on UNIX system?
You can do the Echo $RANDOM. It will return a undefined variable if you are from the C-Shell, just a return prompt if you are from the Bourne shell, and a 5 digit random numbers if you are from the Korn shell. You could also do a ps -l and look for the shell with the highest PID.

What is Boyce Codd Normal form? 
A relation schema R is in BCNF with respect to a set F of functional dependencies if for all functional dependencies in F+ of the form a->b, where a and b is a subset of R, at least one of the following holds: 

* a->b is a trivial functional dependency (b is a subset of a)
* a is a superkey for schema R

What is pure virtual function? 
A class is made abstract by declaring one or more of its virtual functions to be pure. A pure virtual function is one with an initializer of = 0 in its declaration 

Write a Struct Time where integer m, h, s are its members 
struct Time
{
int m;
int h;
int s;
};

How do you traverse a Btree in Backward in-order? 
Process the node in the right subtree
Process the root
Process the node in the left subtree

What is the two main roles of Operating System? 
As a resource manager
As a virtual machine

In the derived class, which data member of the base class are visible? 
In the public and protected sections.