How to add up int pointer values in a linked list in C++? - c++

Question

I've been working at this homework assignment for awhile and I can't figure out what I'm doing wrong. How my program is suppose to work:
User enters as many positive numbers as they so desire,
Numbers are in a linked list,
Numbers entered should be added up,
Divide by the amount of numbers entered,
Resulting in the average,
However, it's not working out as I had intended and I've been playing with this for over 3 hours now. I'd contact my teacher but she hasn't responded to my last message still and I need assistance right away. Thanks in advance.
Note: I need to traverse the list to add up all the entered numbers and count the number of nodes.
#include <iostream>
using namespace std;
int num, total, num_entries = 1;
struct number_node
{
int number;
number_node *next;
};
number_node *head_ptr;
number_node *current_ptr;
int get_number_data(int &number);
void add_node(int &number);
void move_current_to_end();
void display_avg();
void delete_list();
int main()
{
if(get_number_data(num))
{
head_ptr = new number_node;
head_ptr->number = num;
head_ptr->next = NULL;
while(get_number_data(num))
{
add_node(num);
}
display_avg();
delete_list();
}
system("pause");
return 0;
}
int get_number_data(int &number)
{
int keep_data = 1;
cout << "Enter a positive number (Enter a negative number to stop): ";
cin >> num;
if(num < 0)
{
keep_data = 0;
}
return(keep_data);
}
void add_node(int &number)
{
number_node *new_rec_ptr;
new_rec_ptr = new number_node;
new_rec_ptr->number = num;
new_rec_ptr->next = NULL;
move_current_to_end();
current_ptr->next = new_rec_ptr;
}
void move_current_to_end()
{
current_ptr = head_ptr;
num_entries++;
while(current_ptr->next != NULL)
{
current_ptr = current_ptr->next;
total = current_ptr->number + total;
}
}
void display_avg()
{
current_ptr = head_ptr;
cout << "Average = " << total / num_entries << endl;
}
void delete_list()
{
number_node *temp_ptr;
current_ptr = head_ptr;
do
{
temp_ptr = current_ptr->next;
delete current_ptr;
current_ptr = temp_ptr;
}
while(temp_ptr != NULL);
}

Answer 1

Right now you're mixing your data structure (linked list) with what you intend to use it for. Consider splitting your logic into:
Your I/O code.
The linked list implementation.
A function that takes a linked list, and computes the average.

Answer 2

You've got a lot of other stuff there and you didn't say what your code does, but I'd do something like this (untested):
int count = 0;
int total = 0;
for (ptr = head_ptr; ptr != NULL; ptr = ptr->next)
{
total += ptr->number;
count++;
}

Answer 3

I know this won't help you with your homework, but here is a C++ STL program that satisfies your requirements:
As many inputs as the user desires
Numbers are stored in a linked list
Numbers are added up
Calculates and displays average
Good luck with your class.
#include <list>
#include <iterator>
#include <iostream>
#include <algorithm>
#include <numeric>
int main()
{
std::list<double> l;
std::copy(std::istream_iterator<double>(std::cin),
std::istream_iterator<double>(),
std::insert_iterator<std::list<double> >(l, l.begin()));
size_t size = l.size();
if(size)
std::cout << std::accumulate(l.begin(), l.end(), 0.0) / l.size()
<< std::endl;
}
~

Answer 4

Apologies: would have attached a comment to ask this introductory question. But apparently you need a higher rep than i currently have to do so.
#Brandon. Can i get you to clearly state that it is these functions:
int get_number_data(int &number)
void add_node(int &number)
void move_current_to_end()
void display_avg()
and only these that you are allowed to use? (And i quote you: "I just have to have it figure out the total and and # of nodes using those functions"
If so. Why? Have they been specified by your lecturer?