Exercise - Pointer
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  1. #1
    Join Date
    Oct 2013
    Posts
    4

    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?
    Last edited by khelkely; October 17th, 2013 at 09:57 PM.

  2. #2
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    Re: Exercise - Pointer

    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.
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  3. #3
    Arjay's Avatar
    Arjay is offline Moderator / MS MVP Power Poster
    Join Date
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    Posts
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    Re: Exercise - Pointer

    Quote Originally Posted by laserlight View Post
    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.

  4. #4
    Join Date
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    Location
    England
    Posts
    2,020

    Re: Exercise - Pointer

    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.
    All advice is offered in good faith only. You are ultimately responsible for effects of your programs and the integrity of the machines they run on.

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