Exercise - Pointer

Q1: Trace the partial of program below:

1. int v = 8, *r, *s;
2. int *p;
3. int q = 100;
4. p = &q;
5. r = p;
6. *p = 20;
7. p = new int;
8. *r = 30;
9. q = v;
10. s = p;
11. *s = 50;

What are the last values of *p, q, *r, v and *s?
my answer :
*p = 20
q = ?
*r = 30
v = ?
*s = 50

i can't find q and v. But, if q will point whatever v point, so, the value of q is 8 ? am i right ?



Q2 = Given the following codes:
1. int *p , *q , v , nom[5];
2. p = &v;
3. *p = 12;
4. q = p;
5. nom[0] = *q;
6. p = nom;
7. p++;
8. nom[2] = 12;
9. *p = 13;
10. *q = 10;
11. v = 11;
12. *(p+3) = 16;
13. p = &nom[3];
14. *p = 10;
15. p--;

What are the last values of *p, *q, v and nom ?

my answer :
*p = 10
*q = 10
v = 11
nom = ?

i can't find nom .

Q3 : Given below declaration :

Code:

---

struct Node
{
      int  value;
      Node  * next;
 };

---

In the main function, the following codes are given:
1. Node *q, *r;
2. Node *p = new Node; //address of this new Node adalah 10000
3. q = r = NULL;
4. p -> value = 9;
5. p -> next = NULL;
6. q = new Node; //address of this new Node adalah 10050
7. p->next = q;
8. p->next->value = 8;
9. q->next = new Node; //address of this new Node adalah 10100
10. r = q;
11. r-> value = 10;
12. q->next->value = 11;
13. q = q-> next;
14. q -> next = NULL;

What are the last values of p->value and q->value ?

my answer :

p->value = 9
q->value = NULL

Anyway, is it relevant my answer?

I suggest that you pose your questions to one particular community. If you have received no satisfactory answer after a considerable time, then you move on to another community, noting that you previously asked elsewhere.

Anyway, my answer is the same: write a program to find out. Ask if you don't understand why the results are what they are.

Quote:

---

Originally Posted by laserlight

write a program to find out. Ask if you don't understand why the results are what they are.

---

You know, it might not seem like it, but this is the best answer.

If you write a program and spend a couple minutes stepping through the program in a debugger, you can see the exact values of all the variables.

Debugging a program may sound hard but the basics are very easy to learn. If you don't how, please ask.

Being able to debug a program and trace its execution path and inspect variables is an essential part of becoming a programmer. You need to become familiar with using the debugger and tracing through small programs like this is an excellent way to start. As Arjay said in post #3, if you come across problems using the compiler/linker/debugger, just ask us.