Question about linked lists.

This is a discussion on Question about linked lists. within the C++ Programming forums, part of the General Programming Boards category; Hi everyone, I'm studying for my final exam and I am stuck on a review question. The question is as ...

  1. #1
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    Question Question about linked lists.

    Hi everyone,
    I'm studying for my final exam and I am stuck on a review question.

    The question is as follows:

    Consider this code fragment and answer the questions, which follow.

    NODE *p1, *p2,*p3;
    NODE *p, *pFirst, *pNew, *pTemp;

    Question:
    Write the code to allocate memory for nodes at p1, p2, and p3. Do not declare any new variables. Assume that your code will appear after the above fragment, and write only the necessary statements.

    This is what I have come up with. Let me know if I am right or where I went wrong.

    pFirst = NULL;


    pNew = new NODE;
    pNew->link = NULL;
    if (pFirst == NULL)
    {
    pFirst = pNew;
    pTemp = pNew;
    }
    else
    {
    pTemp->link = pNew;
    pTemp = pNode;
    }

  2. #2
    Code Goddess Prelude's Avatar
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    >Write the code to allocate memory for nodes at p1, p2, and p3.
    All this question asks you to do is allocate memory for those three pointers:
    Code:
    try {
      p1 = new NODE;
      p2 = new NODE;
      p3 = new NODE;
    }
    catch ( bad_alloc ) {
      cerr<<"Memory allocation failure\n";
    }
    Done.

    -Prelude
    My best code is written with the delete key.

  3. #3
    Confused Magos's Avatar
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    Re: Question about linked lists.

    Originally posted by cheeisme123
    Code:
    pFirst = NULL;
    
    if(pFirst == NULL)
    {
       ...
    }
    Why check if it's NULL in this case where it's always NULL?
    MagosX.com

    Give a man a fish and you feed him for a day.
    Teach a man to fish and you feed him for a lifetime.

  4. #4
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    Write additional statements to make the nodes at p1, p2, p3 into a forrward-linked list, such that p3 is the first node, p1 is the second, and p2 is last. Assign the address of the first node to pFirst.

    How does this sound:

    p3->link=pFirst;
    p3->link->link=p1;
    p1->link=p2;

  5. #5
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    Another linked question

    I'm studying for my final exam and I am stuck on a review question.

    The question is as follows:

    Consider this code fragment and answer the questions, which follow.

    NODE *p1, *p2,*p3;
    NODE *p, *pFirst, *pNew, *pTemp;

    try {
    p1 = new NODE;
    p2 = new NODE;
    p3 = new NODE;
    }
    catch ( bad_alloc ) {
    cerr<<"Memory allocation failure\n";
    }


    QUESTION:

    Write additional statements to make the nodes at p1, p2, p3 into a forrward-linked list, such that p3 is the first node, p1 is the second, and p2 is last. Assign the address of the first node to pFirst.

    How does this sound:

    p3->link=pFirst;
    p3->link->link=p1;
    p1->link=p2;

  6. #6
    Code Goddess Prelude's Avatar
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    >Write additional statements to make the nodes at p1, p2, p3 into a forrward-linked list, such that p3 is the first node, p1 is the second, and p2 is last.
    Code:
    p3->next = p1; // p3 points to p1
    p1->next = p2; // p1 points to p2
    >Assign the address of the first node to pFirst.
    Code:
    pFirst = p3; // pFirst points to the start, p3
    -Prelude
    My best code is written with the delete key.

  7. #7
    Code Goddess Prelude's Avatar
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    >How does this sound:
    It sounds like you should keep the same questions to a single thread. Double posting is rude, please don't do it.

    -Prelude
    My best code is written with the delete key.

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