I have an assignment to create a PriorityQueue structure and I’m having trouble with this piece of code. When I compile it on my compilator everything’s fine, but I tried submitting it to ideone and I get the following error:
“glibc detected *** ./prog: double free or corruption”.
I was able to track the part that was giving me this error and I found out that what causes the crash is me trying to delete a pointer at the destructor of my class. The problem is that I don’t know why I cant delete it. I don’t know a lot about pointers but I thought that if I used new to allocate memory I had to delete it after using it and I think this is what I’m trying to do. Here is my code:
struct PriorityQueue
{
LinkedList queue; LinkNode *it,*node;
int sz;
PriorityQueue(){
sz=0;
queue.head=NULL;
queue.tail=NULL;
it = NULL;
node=NULL;
}
~PriorityQueue(){
if(node != NULL) //this is causing the error.
delete [] node;
if(it != NULL)
delete [] it;
}
int size(){
return sz;
}
void enqueue(int x){
node = new LinkNode(x,NULL,NULL);
if(sz==0){
queue.insert_head(x);
sz++;
}
else{
if(x <= queue.head->value ){
queue.insert_head(x);
sz++;
}
else if( x>= queue.tail->value ){
queue.insert_tail(x);
sz++;
}
else{
it = queue.head;
for(int k=0;k<sz;k++){
if( (x>= it->value) && (x <= it->next->value) ){
node->next= it->next;
node->previous = it;
it->next->previous = node;
it->next = node;
sz++;
break;
}
it=it->next;
}
}
}
}
int dequeue_min(){
int min = queue.remove_head();
sz--;
return min;
}
int dequeue_max(){
int max= queue.remove_tail();
sz--;
return max;
}
};
int main()
{
PriorityQueue pq;
pq.enqueue(4);
pq.enqueue(2);
pq.enqueue(7);
pq.enqueue(-6);
pq.enqueue(0);
cout << pq.dequeue_min() << endl; // debe imprimir -6
cout << pq.dequeue_min() << endl; // debe imprimir 0
pq.enqueue(3);
cout << pq.dequeue_min() << endl; // debe imprimir 2
cout << pq.dequeue_min() << endl; // debe imprimir 3
return 0;
}
Thanks.
itandnodepoint to objects, not arrays.You cannot use the array form of
delete[]on them.