delete prev elem if..

[xeniox]

Hello I have home work in c++: write function whose delete those elements who next element is even.

For example i have this list: 4 2 2, the result of this function mus be: 2. other example: 4 1 2 2, result: 4 2.

I write such function, but with this examples my function make errorin other way my function works correctly. Where can be error in this function?:

structure:

struct elem 
{
	int n;
	elem *next;
};

function:

void remake(elem *&first)
{
    elem *curr=first;
    elem *prev=NULL;
    elem *pprev=NULL;
       
   while(curr!=NULL)
   {
	   pprev=prev;
       prev=curr;
       curr=curr->next;
                 
       if(curr!=NULL)
	   {
		   if(curr->n%2==0)
		   {
			   if(pprev==NULL)
			   {
				   delete prev;
                                   first=curr;
                                   prev=curr;
			   }
			   else
			   {
				   pprev->next=curr;
				   delete prev;
				   prev=pprev;
			   }
		   }
	   }
   }
};

[dwks]

Can you describe what type of error you are getting? A segmentation fault or something?

Also, remake() is a bad name for a function. Be imaginative.

[xeniox]

Why remake() is bad, i like it. Transform will be better?

Not exactly error I get, but wrong result:
for input data 4 2 2 I get output result -572662307.

I think there is some problems with NULL's somewhere. But I dont know where..

[tabstop]

In your case where you're deleting the head of the list, should prev not get reset to NULL (rather than curr)?

[dwks]

Why remake() is bad, i like it. Transform will be better?

Well, it doesn't tell you anything about what the function does. remove_before_even() would be a better name, for example.