Databases
StackOverflow2013
Postsdbo
POMultiplying two Polynomials in a cpp LinkedList program
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POMultiplying two Polynomials in a cpp LinkedList program
    primarykey
    data
    text
    <p>I'm doing a Polynomials program in C++ that we're supposed to be implementing with a singly-linked list. And yes, this is a homework. I've worked out most of the program and I'm just stuck with my multiplication operator overloading. This is my operator* function:</p> <pre><code>LinkedList operator*(const LinkedList&amp; a, const LinkedList&amp; b) { LinkedList product; Node* nodeA = a.head; Node* nodeB = b.head; int coeff, powr; if (nodeA == NULL &amp;&amp; nodeB == NULL) return product; else if (nodeA == NULL &amp;&amp; nodeB != NULL) return b; else if (nodeA != NULL &amp;&amp; nodeB == NULL) return a; else { while (nodeA != NULL) { while (nodeB != NULL) { coeff = nodeA-&gt;getCoeff() * nodeB-&gt;getCoeff(); powr = nodeA-&gt;getPow() + nodeB-&gt;getPow(); product.addElement(coeff, powr); nodeB = nodeB-&gt;getNext(); } nodeB = b.head; nodeA = nodeA-&gt;getNext(); } } return product; } </code></pre> <p>For reference, I just add a new element to the end of the Linked List for now. </p> <p>Here is my AddElement function:</p> <pre><code>void LinkedList::addElement(int coeff, int powr) { Node *newNode = new Node(); // Set the Node's data newNode-&gt;setPowAndCoefficient(coeff, powr); newNode-&gt;setNextNode(NULL); Node *temp = head; if (temp != NULL) { // Go to the last element of the list while (temp-&gt;getNext() != NULL) { temp = temp-&gt;getNext(); } // temp is now the last element and its next element is null // Set temp's next node to be the newNode temp-&gt;setNextNode(newNode); } else head = newNode; } </code></pre> <p>Node is just my class with private data members coefficent, power and a pointer to the next node. LinkedList is my main class that includes a private Node* head member and public operator overloaded functions and several constructors. The constructor used here is the default constructor in which I just set the head to NULL. </p> <p>I put some cout statments after the second while loop and I multiplied two polynomials to test my multiply function out. </p> <p>So in this case, I have this code in my main.cpp file:</p> <pre><code>LinkedList poly1, poly2, result; // The first polynomial: 3x^3 + 7x^2 - 7 poly1.addElement(3, 3); poly1.addElement(7, 2); poly1.addElement(-7, 0); cout &lt;&lt; "Polynomial A: " &lt;&lt; poly1 &lt;&lt; endl; // The second polynomial: -5x^5 - 14x^3 + 7x^2 + 14 poly2.addElement(-5, 14); poly2.addElement(-14, 3); poly2.addElement(7, 2); poly2.addElement(14, 0); cout &lt;&lt; "Polynomial B: " &lt;&lt; poly2 &lt;&lt; endl; </code></pre> <p>Also, the &lt;&lt; overloaded operator works fine and displays the linked list fine. The problem is when I try to do this:</p> <pre><code>result = poly1 * poly2; </code></pre> <p>I get a segmentation fault. And I don't know why. As I've said, I put cout statements inside the first while loop and this is what I get when I do poly1 * poly2:</p> <pre><code> -15x^17 - 42x^6 + 21x^5 + 42x^3 - 35x^16 - 98x^5 + 49x^4 + 98x^2 + 35x^14 + 98x^3 - 49x^2 - 98 [1] 39009 segmentation fault ~/Desktop/run </code></pre> <p>Yeah, it's pretty ugly, but this is before I add all these stuff together. But anyways, it's essentially right. I just get a segmentation fault after it evaluates the last constant.</p> <p>I have no idea why it's doing this and it only does this for the multiply operator. Other stuff works fine though. I probably have a bug somewhere and I've looked for it these past few hours but I don't know what I've done wrong. Can someone please help? </p> <p>Thanks. </p> <p>My node class:</p> <pre><code>class Node { private: int power; int coefficient; Node *next; public: Node(); // in implementation: coeff = 0, power = 0, next = NULL; Node(const int coeff, const int powr = 1); void setPowAndCoefficient(const int coeff, const int powr); inline int getPow() const { return power; }; inline int getCoeff() const { return coefficient; }; inline void setNextNode(Node *aNode) { next = aNode; }; inline Node *getNext() const { return next; }; }; Node::Node() { coefficient = 0; power = 1; next = NULL; } Node::Node(const int coeff, const int powr) { coefficient = coeff; power = powr; next = NULL; } void Node::setPowAndCoefficient(const int coeff, const int powr) { coefficient = coeff; power = powr; next = NULL; } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USwatabou
    1. USwatabou
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POMultiplying two Polynomials in a cpp LinkedList program
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POMultiplying two Polynomials in a cpp LinkedList program
      1. USwatabou
      1. VTFavorite
    3. VO
      singulars
      1. POMultiplying two Polynomials in a cpp LinkedList program
      1. This table or related slice is empty.
      1. VTModeratorReview
    1. COAre those the simplest polynomials that cause the error?
      singulars
      1. POMultiplying two Polynomials in a cpp LinkedList program
      1. USBeta
    2. COYou haven't shown enough code to pinpoint a problem. The code you have provided is fine. (See: http://ideone.com/AePLI).
      singulars
      1. POMultiplying two Polynomials in a cpp LinkedList program
      1. USjxh
    3. CO@user315052 Well, I could add more code but as I've said, this is the only piece of code that's actually causing an error. Everything else is fine. Plus, if you ignored everything except the operator* function, the Node class (which is pretty simple) and the LinkedList default constructor (which just has "head = NULL" in it), add the cout statement in the first while loop, and run the code, it will produce a segmentation fault after the constant which is what I'm getting.
      singulars
      1. POMultiplying two Polynomials in a cpp LinkedList program
      1. USwatabou
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload