Frequently asked C++ Interview Questions and Answers -6

In C++, what is the difference between method overloading and method overriding?

Overloading a method (or function) in C++ is the ability for functions of the same name to be defined as long as these methods have different signatures (different set of parameters). Method overriding is the ability of the inherited class rewriting the virtual method of the base class.

What methods can be overridden in Java?

In C++ terminology, all public methods in Java are virtual. Therefore, all Java methods can be overwritten in subclasses except those that are declared final, static, and private.

What are the defining traits of an object-oriented language?

The defining traits of an object-oriented langauge are:
* encapsulation
* inheritance
* polymorphism

Write a program that ask for user input from 5 to 9 then calculate the average

int main()
{
int MAX=4;
int total =0;
int average=0;
int numb;
cout<<"Please enter your input from 5 to 9";
cin>>numb;
if((numb <5)&&(numb>9))
cout<<"please re type your input";
else
for(i=0;i<=MAX; i++)
{
total = total + numb;
average= total /MAX;
}
cout<<"The average number is"<
return 0;
}

Can you be bale to identify between Straight- through and Cross- over cable wiring? and in what case do you use Straight- through and Cross-over?

Straight-through is type of wiring that is one to connection, Cross- over is type of wiring which those wires are got switched
We use Straight-through cable when we connect between NIC Adapter and Hub. Using Cross-over cable when connect between two NIC Adapters or sometime between two hubs.

If you hear the CPU fan is running and the monitor power is still on, but you did not see any thing show up in the monitor screen. What would you do to find out what is going wrong?

I would use the ping command to check whether the machine is still alive(connect to the network) or it is dead.

Assignment Operator - What is the diffrence between a "assignment operator" and a "copy constructor"?

Answer1.
In assignment operator, you are assigning a value to an existing object. But in copy constructor, you are creating a new object and then assigning a value to that object. For example:

complex c1,c2;
c1=c2; //this is assignment
complex c3=c2; //copy constructor

Answer2.
A copy constructor is used to initialize a newly declared variable from an existing variable. This makes a deep copy like assignment, but it is somewhat simpler:

There is no need to test to see if it is being initialized from itself.
There is no need to clean up (eg, delete) an existing value (there is none).
A reference to itself is not returned.

"mutable" Keyword - What is "mutable"?

Answer1.
"mutable" is a C++ keyword. When we declare const, none of its data members can change. When we want one of its members to change, we declare it as mutable.

Answer2.
A "mutable" keyword is useful when we want to force a "logical const" data member to have its value modified. A logical const can happen when we declare a data member as non-const, but we have a const member function attempting to modify that data member. For example:

class Dummy {
 public:
   bool isValid() const;
 private:
   mutable int size_ = 0;
   mutable bool validStatus_ = FALSE;
     // logical const issue resolved
};

bool Dummy::isValid() const
 // data members become bitwise const
{
 if (size > 10) {
   validStatus_ = TRUE; // fine to assign
   size = 0; // fine to assign
 }
}

Answer2.
"mutable" keyword in C++ is used to specify that the member may be updated or modified even if it is member of constant object. Example:

class Animal {
 private:
   string name;
   string food;
   mutable int age;
 public:
 void set_age(int a);
};

void main() {
 const Animal Tiger(’Fulffy’,'antelope’,1);
 Tiger.set_age(2);
   // the age can be changed since its mutable
}

RTTI - What is RTTI?

Answer1.
RTTI stands for "Run Time Type Identification". In an inheritance hierarchy, we can find out the exact type of the objet of which it is member. It can be done by using:

1) dynamic id operator
2) typecast operator

Answer2.
RTTI is defined as follows: Run Time Type Information, a facility that allows an object to be queried at runtime to determine its type. One of the fundamental principles of object technology is polymorphism, which is the ability of an object to dynamically change at runtime.

STL Containers - What are the types of STL containers?

There are 3 types of STL containers:

1. Adaptive containers like queue, stack
2. Associative containers like set, map
3. Sequence containers like vector, deque

Bitwise Operations - Given inputs X, Y, Z and operations | and & (meaning bitwise OR and AND, respectively), what is output equal to in?

   output = (X & Y) | (X & Z) | (Y & Z);

courtesy:DEVFYI - Developer Resource - FYI