Double Linked List Insertion Sorting Bug - c++

Question

I have implemented an insertion sort in a double link list (highest to lowest) from a file of 10,000 ints, and output to file in reverse order.
To my knowledge I have implemented such a program, however I noticed in the ouput file, a single number is out of place. Every other number is in correct order.
The number out of place is a repeated number, but the other repeats of this number are in correct order. Its just strange how this number is incorrectly placed. Also the unsorted number is only 6 places out of sync.
I have looked through my program for days now with no idea where the problem lies, so I turn to you for help.
Below is the code in question,
(side note: can my question be deleted by myself? rather my colleges dont thieve my code, if not how can it be deleted?)
void DLLIntStorage::insertBefore(int inValue, node *nodeB)
{
node *newNode;
newNode = new node();
newNode->prev = nodeB->prev;
newNode->next = nodeB;
newNode->value = inValue;
if(nodeB->prev==NULL)
{
this->front = newNode;
}
else
{
nodeB->prev->next = newNode;
}
nodeB->prev = newNode;
}
void DLLIntStorage::insertAfter(int inValue, node *nodeB)
{
node *newNode;
newNode = new node();
newNode->next = nodeB->next;
newNode->prev = nodeB;
newNode->value = inValue;
if(nodeB->next == NULL)
{
this->back = newNode;
}
else
{
nodeB->next->prev = newNode;
}
nodeB->next = newNode;
}
void DLLIntStorage::insertFront(int inValue)
{
node *newNode;
if(this->front == NULL)
{
newNode = new node();
this->front = newNode;
this->back = newNode;
newNode->prev = NULL;
newNode->next = NULL;
newNode->value = inValue;
}
else
{
insertBefore(inValue, this->front);
}
}
void DLLIntStorage::insertBack(int inValue)
{
if(this->back == NULL)
{
insertFront(inValue);
}
else
{
insertAfter(inValue, this->back);
}
}
ifstream& operator>> (ifstream &in, DLLIntStorage &obj)
{
int readInt, counter = 0;
while(!in.eof())
{
if(counter==dataLength) //stops at 10,000
{
break;
}
in >> readInt;
if(obj.front != NULL )
{
obj.insertion(readInt);
}
else
{
obj.insertBack(readInt);
}
counter++;
}
return in;
}
void DLLIntStorage::insertion(int inValue)
{
node* temp;
temp = this->front;
if(temp->value >= inValue)
{
insertFront(inValue);
return;
}
else
{
while(temp->next!=NULL && temp!=this->back)
{
if(temp->value >= inValue)
{
insertBefore(inValue, temp);
return;
}
temp = temp->next;
}
}
if(temp == this->back)
{
insertBack(inValue);
}
}
Thankyou for your time.

Answer 1

I don't like this part
else
{
while(temp->next!=NULL && temp!=this->back)
{
if(temp->value >= inValue)
{
insertBefore(inValue, temp);
return;
}
temp = temp->next;
}
}
if(temp == this->back)
{
insertBack(inValue);
}
Imagine what happens if inValue is greater than all values except this->back->value. It gets inserted at the end instead before this->back. By the way, You are inserting equal integers in the reversed order, they are read. For integers it doesn't matter that much, but it could if You inserted other objects. I would change the code of the insertion method to this:
node* temp;
temp = this->front;
while(temp!=NULL)
{
if(temp->value > inValue)
{
insertBefore(inValue, temp);
return;
}
temp = temp->next;
}
insertBack(inValue);

Answer 2

Just some remarks.
while(!in.eof())
This will not stop the inside of the loop from seeing an EOF error. You want
while ( in >> readInt )
Also,
if(this->front == NULL)
and
void DLLIntStorage::insertion(int inValue)
{
node* temp;
temp = this->front;
if(temp->value >= inValue)
do not mix. Either the front can be NULL, or it cannot. Likewise, you need to decide whether to use temp->next!=NULL or temp!=this->back, but not both, as a loop termination condition.
My guess would be that some inconsistency between multiple linking conventions is causing the errant value to get pushed into the middle of the list.