linked list prob

[azwraith69]

hello,,:)

i have problem doing a FOR loop in my linked list,, it doesn't start the loop,, i don't know why...

class node
{
public:
    node(int number, node*nxt):number(number),nxt(nxt){}
    int getNumber(){return number;}
    void setNumber(int number){this->number=number;}
    node* getNxt(){return nxt;}
    void setNxt(node *){this->nxt=nxt;}
private:
    int number;
    node *nxt;
};

bool mergeList(node *&result, node *list1, node *list2)
{
    if(!result)
    {
		[B]for(node *i=list1, *j=list2; i->getNxt()!=NULL || j->getNxt()!=NULL;\
			i=i->getNxt(), j=j->getNxt())
		{
			if(!result)
			{
				if(i->getNumber() <= j->getNumber())
				{
					result = i;
					result->setNxt(j);
					result = j;
					result->setNxt(NULL);
				}
				else
				{
					result = j;
					result->setNxt(i);
					result = i;
					result->setNxt(NULL);
				}
			}
			else
			{
				if(i->getNumber() <= j->getNumber())
				{
					if(i->getNumber() <= result->getNumber())
						return false;
					else
					{
						result->setNxt(i);
						result = i;
						result->setNxt(j);
						result = j;
						result->setNxt(NULL);
					}
				}
				else
				{
					if(j->getNumber() <= result->getNumber())
						return false;
					else
					{
						result->setNxt(j);
						result = j;
						result->setNxt(i);
						result = i;
						result->setNxt(NULL);
					}
				}
			}
		}[/B]
		return true;
    }
    else
        return false;
}

the loop doesn't run,, and i'm sure RESULT is empty when i passed it (function always return TRUE)...

thx...

[kbshibukumar]

Is the value of result != NULL when you invoke the function? I don't see you do a new operation on result anywhere in the function.

As you stated, if it is really non-null, the program would crash because you are accessing the member functions of result in a number of places.

[azwraith69]

Is the value of result != NULL when you invoke the function? I don't see you do a new operation on result anywhere in the function.

As you stated, if it is really non-null, the program would crash because you are accessing the member functions of result in a number of places.

thx.. but i think you misunderstood some things,, i need the RESULT to be empty.. not "non-null"... if it is non-null, then false..

do i need a new? i already assigned i(a node) to result..
correct me if im wrong..

what i dont understand is why my FOR loop doesn't run..

thx!

[skatamatic]

For loops are designed mainly for integer incrementation. They support other datatypes, but this will often result in confusing problems like this. Instead, use a while loop.

while (i!=NULL && j!=NULL)
{
//do stuff
i=i->GetNext();
j=j->GetNext();
}

[kbshibukumar]

OK.. I understood.
However, I think your sequence would enter the for loop only if both list1->getNxt() == NULL and list2->getNxt() == NULL because of the terminationg condition in for loop. Are you meaning the same logic?