C++ Bank

1. Predict the output
main()
{
    float me = 1.1;
    double you = 1.1;
    if(me==you)
        cout << "C++ " ;
    else
        cout << "Programming";
}
Answer: Programming
Explanation: Double values takes the value more accurately than that of float.

2. Find the type of error in the following code snippet
main()
{
    extern int i;
    i=20;
    cout << i;
}
Answer: Compiler error
Explanation: The declaration of 'i' should be available out of main, because, 'extern int i' is not a declaration.

3. Predict the output
main()
{
    char *p;
    cout << sizeof(*p) << " " << sizeof(p);
}
Answer: The answer is compiler dependent, because, Turbo C/C++ is 16 bit based compiler.
g++            : 4 1
Turbo C++ : 2 1

4. Predict the output
main()
{
    cout << "\nab";
    cout << "\bsi" ;
    cout << "\rha";
}
Answer: hai 
Explanation: \n takes to the new line and then ab is printed
Result: ab
\b removes the last character in that line ( just as backspace does ) and si is printed
Result: asi
\r takes the cursor to the starting position of that line and ha is printed
Result: hai
Note that the existing characters are replaced

5. Predict the output
main()
{
    int i = -1;
    +i;
    cout << "i = " << i << ", +i = " << +i;
}
Answer: i = -1, +i = -1

6. Predict the output
void afunction(int *x)
{
   x = new int;
   *x = 12;
}
int main()
{
   int v = 10;
   afunction(&v);
   cout << v;
   return 0;
}
Answer: 10
Explanation: Though the address of v is assigned to x and the content of x changes, value of v doesn't change because, x is then assigned a new memory location by calling the new operator.

7. What would be the output of cout << abs(-16);
Answer: 16

8. How long does this loop run ?for(int x=0; x=3; x++)Answer: Infinitely
Explanation: The condition is x=3, which assigns 3 to x each time and the condition is given as 3 ( non-zero value ) and so, the loop doesn't terminate.

9. Evaluate!(1&&1||1&&0) Answer: False 

10. What does non-global variables default to ? 

Answer: auto

11. Which of the following function prototype is perfectly acceptable?Answer: int Function(int Tmp = Show());Explanation: This is nothing but the value returned by the Show() method is the default argument value for Tmp.
12. Which of the following statement is correct?Answer: A function can be overloaded more than once.Explanation: The rest of the statements, which are as follows, are incorrect.1. Two functions having same number of argument, order and type of argument can be overloaded if both functions do not have any default argument.2. Overloaded function must have default arguments.3. Overloaded function must have default arguments starting from the left of argument list.
13. What happens when we try to compile the class definition in following code snippet?class Birds {}; class Peacock : protected Birds {};Answer: It will compile successfully.
14. Which of the following statements are correct?1. Once a reference variable has been defined to refer to a particular variable it can refer to any other variable. 2. A reference is not a constant pointer.Answer: Both 1 and 2 are incorrect.
15. What will be the output of the following program?class Disp{    int x;    public:    Disp(int xx, float yy)    {         cout<< char(yy);    } }; int main() {     Disp *p = new Disp(35, 99.50f);     return 0; }Answer: ASCII equivalent of 99 (Output: c)Explanation: 99.5 when typecasted to char, undergoes an intermediate typecasting to int as 99. Then, it's equivalent character value (c) is displayed.

16. Which of the following are supported by C++?Answer: All (structure, union and class)

17. What will be the output of the following program?bool v = -1; printf("%d", v);

• Answer: 1
• Explanation: Every non-zero value is treated as true and the equivalent integer for true is 1.

18. Will these functions cause ambiguity error?

void function(int a = 10); void function();

• Answer: Depends upon the function call
• Explanation: Unless the function is called with no arguments, there is no ambiguity error.
• function(2)  -->  Does not cause ambiguity error
• function()  --> Causes ambiguity error
• No function call --> Does not cause ambiguity error

19. What is sizeof ?

• Answer: Operator
• Explanation: sizeof is an unoverloadable operator. 

20. Can a bool variable and an integer be compared in C++?

• Answer: Yes
• Explanation: bool is also an integer data type, which can store only 0 or 1.

21. What would be the advantage of returning a reference from a function?

Answer: Function call can be in the left hand side of the assignment operator and a reference is more efficient than returning a copy

22. Choose the incorrect statement.

Answer: Friend keyword can be used on main()

Explanation: main() is not inside any class and hence friend can not be used for main.

23. How can we make a class abstract?

Answer: By making all member functions constant

24. Predict the output 

class Sona 

{ 

   public: 

   int x; 

}; 

int main() 

{ 

   Sona *p = new Sona(); 

   (*p).x = 10; 

   cout<< (*p).x << " " << p->x << " " ; 

   p->x = 20; 

   cout<< (*p).x << " " << p->x ; 
}
Answer: 10 10 20 20

Explanation: Both (*p).x and p->x are the same.

25. What will be the output of the following program? 

class Sona 

{

   static int x; 

   public: 

   static void SetData(int xx) 

   {

      x = xx; 

   } 

   void Display() 

   { 

      cout<< x ; 

   } 

}; 

int Sona::x = 0; 

int main() 

{ 

    Sona::SetData(33); 

    Sona::Display(); 

}
Answer: 33

26. Which among the following are object-oriented concepts ?Answer: All the three (Polymorphism, encapsulation and inheritance)

27. Which of the following is not a type of constructor?Answer: Friend constructor
28. Which of the following concepts means determining at run-time what method to invoke?Answer: Data binding

• 29. Which of the following term is used for a function defined inside a class?
• Answer: Member function

30. cout is a/anAnswer: object

• Explanation: cout is an ostream object and cin is an istream object.
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