POINTER EXERCISES

1. What is printed by the following code?

#include<iostream>

using namespace std;

void main()

{

int *p1, *p2;

int number, amount;

number = 0;

amount = 25;

cout << number << ' ' << amount << endl;

p1 = &number;

cout << number << ' ' << *p1 << endl;

p2 = p1;

cout << number << ' ' << *p1 << ' ' << amount<< ' ' << *p2 << endl;

*p2 = 509;

cout << number << ' ' << *p1 << ' ' << amount << ' ' << *p2 << endl;

}

2. A C++ program contains the following statements:

float a,*pa;

float b, *pb;

float c;

a = 3.0;

b = 1.9;

pa = &a;

*pa = 3*a;

pb = &b;

*pb += 0.5;

c = *pa +*pb;

Suppose each floating-point number occupies 4 bytes of memory. Assume further that the address of variable a is 128800, the address of variable b is 128804, and the address of variable c is 128808. 

Draw a layout of memory, its variables and its pointers. Then answer the following questions.

ii) What value is assigned to pa?_______________________

ii) What value is represented by *(&a)? ________________________ 

iii) What value is represented by *pa? __________________________

iv) What value is represented by &(*pb)? _______________________

v)  What value is assigned to c? ____________________________

vi) What value is assigned to pb? ___________________________

3. Suppose the following:

int array[25];

int *p;

How can we use the pointer p to set all elements of array to zero?

4. What is printed by the following code?

#include<iostream>

using namespace std;

int main()

{

int *p, *q;

p = new int;

q = new int[4];

*p = 50;

*q = 25;

for (int i = 1; i < 4; i++)

q[i] = *p;

for (int i = 0; i < 4; i++)

cout << q[i] << ' ';

delete p;

delete [] q;

}

5. Pointers to classes

#include<iostream>

using namespace std;

class twoNums

{

public:

void setOne(int);

void setTwo(int);

void nicePrint();

private:

int one;

int two;

};

int main()

{

twoNums *ptr;

ptr = new twoNums;

(*ptr).setOne(56);

(*ptr).setTwo(23);

(*ptr).nicePrint();

//another way

ptr->setOne(45);

ptr->setTwo(87);

ptr->nicePrint();

}

void twoNums::setOne(int x)

{

one = x;

}

void twoNums::setTwo(int x)

{

two = x;

}

void twoNums::nicePrint()

{

cout <<"* * * ONE: " << one << " * * *" << endl;

cout <<"* * * TWO: " << two << " * * *" << endl;

}

6. // example on constructors and destructors from: //http://www.cplusplus.com/doc/tutorial/classes/

7. // pointer to classes example from //http://www.cplusplus.com/doc/tutorial/classes/