Thread: Linked lists questions

I know this is getting repetitive. Pretty ridiculous, i need a Live breathing teacher, If anyone is out there PLEASE pm me. I am willing to pay you for your time. Me paying you will save me money actually. I am not sure on the rules of the website about asking for help, im very desperateactually. have 2 assignments and a final in about 3 weeks. and still dont see everything the book is trying to teach, and the online teacher doesnt clarify.

anyway,

My program is falling apart. I'm talking very bad. i scrapped the whole thing because i had to change the insertion.
The goal of what i am looking to do is one thing, then i can move on to something else .
Insert a number in if the HeadPtr is empty or NULL.

I've tried
if (HeadPtr==NULL)
{
do something;
}

and

if (HeadPtr==0)
{
do something;
}

what is it that is needed to get to the inside of the if statement?

this is the whole program i am starting over with.

Code:

#include <iostream>
using namespace std;

/* Recursive functions
insertion
retrieval
pointer based sorted linked list of integers
also if 0 is entered it keeps inserting until 0 is entered.
*/


struct node
{
   int item;
   node *next;
};


// takes in the head pointer 
// item to be inserted
//building the list here

void insertion(node *HeadPtr, int NumberToInsert) 
{

if (HeadPtr=NULL) //If the HeadPtr is empty insert the number
{

HeadPtr->item=NumberToInsert;
cout << "The HeadPtr->item is : " << HeadPtr->item << endl;
} //end if

}

void traverser (node *HeadPtr) {
     cout << "Using Traverser the HeadPtr->item is :" << HeadPtr->item << endl;
}

int main() {
int number;
node *HeadPtr=new node;
HeadPtr==NULL;

while (number!=0) 
{
cout << "Please insert the first number: "; 
cin >> number;
}
insertion( HeadPtr, number);
//traverser(HeadPtr);
   system("pause");
    return 0;
}

ok, I found the indent feature on the Dev-CPP compiler and the "find matching braces " feature and enabled it.

For the program, I am trying to fill the HeadPtr only if it is empty.
My questions are.
1. Is a new node an empty node?
2. Is a node pointing to NULL an empty node?
3. If 1, or 2 arent empty nodes what is an empty node?


My program below does not output what is in the if statement. The goal is to fill it only if the HeadPtr is empty.

Code:

#include <iostream>
using namespace std;

struct node
{
   int item;
   node *next;
};

void insertion( node *&HeadPtr, int NumberToInsert)
{    
     if (HeadPtr == new node)
     {
	  	cout << "Inside first if " << endl;
     } //end if
		
}// end insertion

int main() 
{   
    int number= -1;
    node *HeadPtr=new node;
   
    insertion (HeadPtr, number);
    system("pause");
    return 0;
} //end main