Thread: 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?

Instead of asking us if you are right, write programs to find out. If you don't understand why (or if you suspect undefined behaviour), that's when you should ask us