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POProblem either adding to or traversing a linked list
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  1. POProblem either adding to or traversing a linked list
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    copied!<p>I have a problem either adding to or traversing a linked list. The main item class is used by another class but I can add the correct number of these but it looks like when I add more data to the list the app no longer works.</p> <p>I am not sure exactly where the error is. I know that when I try to traverse the list the application crashes. Any ideas or any improvements would be appreciated.</p> <p>I can make the crash not happen by changing the AddOccurence method to not do the while loop.</p> <p>Do </p> <pre><code>void Item::AddOccurence(int Item,int placeInLine){ ItemOccurence* ocr=myHead; if(ocr) { } </code></pre> <p>instead of</p> <pre><code>void Item::AddOccurence(int Item,int placeInLine){ ItemOccurence* ocr=myHead; while(ocr) { } </code></pre> <p>Basically hitting the first node but no more.</p> <p>I have an object that contains a list. Here is the .h file #include using namespace std;</p> <pre><code>class ItemOccurence{ public: ItemOccurence(int line,int placeInLine,ItemOccurence* link=NULL) :myLine(line),myPlaceInLine(placeInLine),myLink(link){} int myLine; int myPlaceInLine; ItemOccurence* myLink; }; class Item { public: Item(); Item(string Item,int line,int placeInLine); virtual ~Item(); void deallocate(ItemOccurence* p); void AddOccurence(int Item,int placeInLine); string myItem; ItemOccurence* myHead; private: bool isEmpty(); }; </code></pre> <p>And the .cpp file</p> <pre><code>#include "Item.h" #include &lt;string&gt; #include&lt;iostream&gt; using namespace std; Item::Item(string Item,int line,int placeInLine):myHead(NULL){ myItem=Item; myHead= new ItemOccurence(line,placeInLine,NULL); } Item::Item():myHead(NULL){ myHead=0; } Item::~Item() { deallocate(myHead); myHead=0; } void Item::deallocate(ItemOccurence* p){ ItemOccurence* tmp; while(p){ tmp=p; p=p-&gt;myLink; delete tmp; } } void Item::AddOccurence(int Item,int placeInLine){ ItemOccurence* ocr=myHead; while(ocr) { cout&lt;&lt;"orrucence head while adding " &lt;&lt; myHead-&gt;myLine &lt;&lt; " " &lt;&lt; myHead-&gt;myPlaceInLine &lt;&lt;"\n"; ocr=ocr-&gt;myLink; } myHead = new ItemOccurence(Item,placeInLine,myHead); return; } bool Item::isEmpty(){ if(myHead) return false; else return true; } </code></pre> <p>EDIT: I updated AddOccurence to be.</p> <pre><code>void Item::AddOccurence(int line,int placeInLine){ ItemOccurence* prev = myHead; ItemOccurence* curr = myHead-&gt;myLink; while(curr){ prev=curr; curr=curr-&gt;myLink; } // insert new ItemOccurence cout&lt;&lt;"adding " &lt;&lt;line&lt;&lt; " and " &lt;&lt; placeInLine &lt;&lt;"\n"; prev-&gt;myLink = new ItemOccurence(line,placeInLine); return; } </code></pre> <p>But I am still crashing. I am trying to debug but not sure what to look for.</p>
 

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