Thread: Deleting duplicates in a linked list

I need to create a function that deletes the duplicates from a linked list this , I think looks right but it causes an application error saying the memory at a certain location could not be read

void delrep (node *&head)
{ node *previous = head;

for (node *head2 = head ; head2->link != NULL;head2=head2->link)
{

for (node *compare =head->link;compare ->link !=NULL; compare=compare ->link)
{

if ( compare ->data == head2->data)
{

previous->link = compare->link;

delete compare;

if(compare->link == NULL)

break;

}

previous = compare;

}

}

}
Any ideas whats wrong with it?

first guess--look at the lines below as copied from posted code:

delete compare;

if(compare->link == NULL)

break;

}

previous = compare;


Now ask yourself what is the value of compare->link and compare after compare is deleted?????

Is this an ordered list? You might have an easier time getting rid of duplicates in a sorting algorithm.

Is it possible to stp the pointer at the node before the one I want to delete like loop until the pointer ->link-> data, sort of.I need to create a pointer pointing at the node before the one I want to remove. How?

is this any closer

void delrep (node *&head)
{ node *remove = head;

for (node *head2 = head ; head2->link != NULL;head2=head2->link)
{
int i =1;
for (node *compare =head->link;compare ->link !=NULL; compare=compare ->link)
{ i++;

if ( compare ->data == head2->data)
{ node *bridge = head ;
for( int x =1 ;x < i-1; x++)
{
bridge = bridge ->link;
}

remove->link = compare->link;
bridge ->link = compare ->link ;

delete remove;

//if(compare->link == NULL)

//break;

}

//previous = compare;

}

}

}

Zen,
I tried adding your code , I get some error message when I run it

did I add it right?

void delrep (node *head)
{ node *remove = head;

node *head2;
head2 = head;
while (head2->link!=NULL)
{

for (node *compare =head;compare ->link !=NULL; compare=compare ->link)
{


if ( compare ->data == head2->data)
{
node* iterator = head;
node* prevnode;
prevnode = new node;

if (iterator != NULL)
{
while(iterator->link!=compare)
iterator=iterator->link;
};

prevnode=iterator;

compare->link= remove ;
prevnode ->link = compare ->link ;

delete remove;
remove = NULL;


}