Searching for data in a linked list - c++

Question

The first part of my program is to extract specific data from a file and insert it into a linked list. I successfully created that part of the program but I'm having difficulty searching through my linked list and printing data. This is my code so far:
struct Country
{
string name;
double population;
};
struct Node
{
Country ctry;
Node *next;
};
Node *world;
void makeList(Node *&world);
void printCountry (Node *&world, string name);
int main ()
{
string name;
makeList(world);
printCountry (world, name);
return 0;
}
void makeList(Node *world)
{
ifstream inFile("population.csv");
if (!inFile.fail())
{
cout << "File has opened successfully." << endl;
}
else
{
cout << "File has failed to open." << endl;
exit(1);
}
double temp, temp1, temp2, temp3, population;
string countryName;
Node *top = new Node;
world = top;
while (!inFile.eof())
{
top -> next = NULL;
inFile >> temp >> temp1 >> temp2 >> temp3 >> population;
getline (inFile, countryName);
top -> ctry.population = population;
top -> ctry.name = countryName;
if (!inFile.eof())
{
top -> next = new Node;
top = top -> next;
}
}
// check if list is created successfully
while (world -> next != NULL)
{
cout << world -> ctry.population << " " << world -> ctry.name << endl;
world = world -> next;
}
}
void printCountry (Node *world, string name)
{
string countryToFind;
cout << "What country do you want to find? " << endl;
cin >> countryToFind;
while (world != NULL)
{
if (world -> ctry.name == countryToFind)
{
cout << "Country has been found: " << world -> ctry.name << " has a population of "
<< world -> ctry.population << endl;
break;
}
else
{
if (world -> next == NULL)
{
cout << "End of file" << endl;
break;
}
world = world -> next;
}
}
}
When I run the printCountry, it just searches through the list and prints End of file. What did I do wrong in the printCountry?

Answer 1

you should really separate
1) data structure (linked list)
2) CSV parser
3) loading the parsed data to the linked list.
Here's an example using C#.
public class LinkedList<T> : IEnumerable<T>
{
private class Node<T>
{
public T Value { get; set; }
public Node<T> Next { get; set; }
}
private Node<T> _startingNode;
public void Add(T item)
{
//define the next node
var nextNode = new Node<T>()
{
Value = item
};
//add the node to the end
Node<T> lastNode = this.GetLastNode();
if (lastNode == null)
{
this._startingNode = nextNode;
}
else
{
lastNode.Next = nextNode;
}
}
public IEnumerator<T> GetEnumerator()
{
Node<T> lastNode = this._startingNode;
while (lastNode != null)
{
yield return lastNode.Value;
if (lastNode.Next == null)
{
yield break;
}
lastNode = lastNode.Next;
}
}
IEnumerator IEnumerable.GetEnumerator()
{
throw new NotImplementedException();
}
private Node<T> GetLastNode()
{
var lastNode = this._startingNode;
while (lastNode != null)
{
if (lastNode.Next == null)
{
break;
}
lastNode = lastNode.Next;
}
return lastNode;
}
}
public class Program
{
public static void Main()
{
//load the list
var numberList = new LinkedList<int>();
numberList.Add(100);
numberList.Add(200);
numberList.Add(300);
numberList.Add(400);
//do something with it
foreach (var item in numberList)
{
Console.WriteLine("Item {0}", item);
}
}
}