Sorting a linked list.

This is a discussion on Sorting a linked list. within the C++ Programming forums, part of the General Programming Boards category; Trying to sort a linked list. I have two classes. class listNode { public: int coef; int expo; listNode *next; ...

  1. #1
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    Sorting a linked list.

    Trying to sort a linked list. I have two classes.
    class listNode {
    public:
    int coef;
    int expo;
    listNode *next;
    };


    class LList {
    private:
    listNode *head;
    listNode *tail;
    public:
    void read()
    void sort();

    };

    I read in the two numbers coef and expo. I need to sort it in accending order by expo. My sort function is
    void LList::sort() {

    listNode *temp;
    listNode *temp2;

    temp = head;
    temp2 = temp->next;
    int CC = 0;
    // counter is global and is size of list
    while(CC != counter) {

    if(temp->expo <= temp2->expo) {
    head = temp2;
    head->next = temp;
    }

    CC++;
    }

    }

    It goes into an infinite loop then crashes.
    Anyone offer advice on the problem? Thanks

  2. #2
    Registered User hk_mp5kpdw's Avatar
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    By using the STL list template object it is much easier to do this:
    Code:
    class listNode {
    public:
        int coef;
        int expo;
        bool operator<(const listNode& rhs)
        {
            return expo < rhs.expo;
        }
    };
    Create a linked-list of listNode objects called MyList (for instance) by saying list<listNode> MyList;. The < operator for the class is used by the sort function built into the list template. To sort the list just say something like MyList.sort(). You may want to add some other things to the class like constructors and what not but in any case, this way is much easier and less error prone.
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
    -Christopher Hitchens

  3. #3
    Registered User The Dog's Avatar
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    I think the problem lies here:
    Code:
    while(CC != counter) {
    
       if(temp->expo <= temp2->expo) {
          head = temp2;               //temp2 never changes
          head->next = temp;      //temp never changes
       }
       CC++;
    }

  4. #4
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    hk_mp5kpdw I did that with list. But when I go to print it out I get the same list printed. Here is my method

    void LList:rint() {
    listNode *temp;
    temp = head;

    while(temp != NULL) {
    std::cout << temp->coef << " " << temp->expo << " ";
    temp = temp->next;
    } // end while

    cout << endl << endl;
    } // end function

    I am thinking this has something to do with head and tail in the LList class not being changed. Offer anymore advice on how to do this? Thanks again.

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