Q1: Explain why the two calls to function g produces different results in each case:
#include
using namespace std;
class X {
int x;
public:
X() { x = 10; }
void f() { cout << "f called " << x << endl; }
};
class Y : public X {
int y;
public:
Y() { y = 20; }
void g() { cout << "g called" << y << endl; }
};
int main() {
X* a = new X;
Y* b = new Y;
((Y*)a)->g();
a = b;
((Y*)a)->g();
}
Q2:
Given the following two classes, Point and Circle:
class Point {
public:
void name() {
cout << "Point" << endl; } }; class Circle: public Point { public: void name() { cout << "Circle" << endl; } }; Which polymorphic treatment can you apply to the above code to make the following code snippet print "Circle"? Point* p = new Circle; p->name();
Q3:
Assuming polymorphism has been applied to the previous Point and Circle class hierarchy, what does the following statement print? And why?
Point p = Circle();
p.name();
Q4:
Given the following:
ClassA a(“C++”);
ClassB b(a);
ClassB *pB = &a;
the invocation
pB -> eval();
invokes the ClassA instance of eval(), where as
b.eval();
invokes the ClassB instance.
Why is that?
Q5:
Given the following class declaration for Pasadena with its set of class members, in which pstrC addresses a dynamic character array:
class Pasadena {
public:
~Pasadena();
…
private:
char* ptrC;
int iVal;
float fVla;
};
Implement the appropriate destructor outside of the Pasadena class.
For the following 7 questions you are asked to identify instance(s) of ClassA at run time in the following code snippet:
ClassA global;
ClassA func(ClassA param) {
ClassA local = param;
ClassA *heap = new ClassA(global);
*heap = global;
ClassA arr[4] = { local, *heap };
return *heap;
}
Q6-12 CHOOSE TRUE/FALSE
6.ClassA global; // this creates an instance of ClassA
7.ClassA func(ClassA param) {…} // this creates an instance of ClassA
8.ClassA local = param; // this creates an instance of ClassA
9.*heap = new ClassA(global); // this creates an instance of ClassA
10.*heap = global; // this creates an instance of ClassA
11.ClassA arr[4] = { local, *heap }; // this creates instance(s) of ClassA
12.return *heap; // this creates an instance of ClassA
Q13:
In your previous lab assignment and quiz you were given the following class Matrix and implemented its operator[ ] method that makes the following statements possible:
Matrix m;
cout << m[0]; // prints 0 cout << m[1]; // prints 1 ... cout << m[9]; // prints 9 Suppose that you now have this Matrix class with a dynamically allocated 2D array: class Matrix { public: Matrix() { _2DArray = newint*[10]; for (inti = 0; i < 10; ++i) { _2DArray[i] = newint[10]; for (intj = 0; j < 10; ++j) _2DArray[i][j] = j; } } ~Matrix() { for (inti = 0; i < 10; ++i) { delete[] _2DArray[i]; } delete[] _2DArray; } private: int** _2DArray; }; Write (implement) an overloaded operator function [ ][ ] (you may have to think creatively for this) such that the following is possible. Note calling m[row][col] is the same as if _2DArray[row][col] is called: Matrix m; cout << m[0][0]; // prints 0 cout << m[0][1]; // prints 1 ... cout << m[0][9]; // prints 9 ... cout << m[9][0]; // prints 0 ... cout << m[9][9]; // prints 9 HINTS: Generally speaking to provide multidimensional array access namely to implement a 3D array access a[i][j][k] = x, operator[] has to return a reference to a 2D plane, which has to have its own operator[] which returns a reference to a 1D row, which has to have operator[] that returns a reference to the element. You get the picture. This question asks for implementation of a 2D array access namely a[i][j] = x, involving slightly less complicated logic. Q14: What is wrong with the following code snippet? Please explain the mistake if any and its correction. int size; cin >> size;
int* arrs = new int[size];
for (int i=0; i
}
delete arrs;
Q15:
What is wrong with the following code snippet from the logical standpoint (not syntax standpoint)?
class Point {
private:
int x, y;
public:
Point(int u, int v) : x(u), y(v) {}
int getX() { return x; }
int getY() { return y; }
};
int main() {
Point* p = new p(5, 3);
std::cout << p->x << " " << p->y;
return 0;
}
Q16:
Implement a single constructor for class Point that, if called with 0 argument, initializes an instance of Point to the origin, or (0, 0). If the constructor is called with two arguments x and y, it creates a Point instance located at (x, y).
Hint: You will need to use default arguments
Q17:
Given a class Point, what would happen if its constructor were private?
Q18:
What is wrong with the following header file from syntax standpoint? Please explain the mistake if any and its correction.
#ifdef _CPPLIST_APPLY_H#define _CPPLIST_APPLY_H
class ApplyFunction {protected:
virtual int function( int x ) const = 0;public:
void apply() const;
virtual ~ApplyFunction() {}
};
#endif //_CPPLIST_APPLY_H
