Cannot convert parameter 1 from Person to Person *[] - c++

Question

I'm trying to make program that reads from a file and adds to a binary tree, but when I try to compile I get an error:
"Error 1 'treePersons::display' : cannot convert parameter 1 from 'Node *' to 'Person *[]'"
The error appears in the call to display() in main()
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
struct Person{
int social;
int birthday;
string first;
string last;
string state;
double balance;
Person();
Person(int s, int b, string f, string l, string t, double a)
{
social = s;
birthday = b;
first = f;
last = l;
state = t;
balance = a;
}
};
struct Node{
Person data;
Node *left;
Node *right;
Node();
Node(Person x){
data = x;
left = NULL;
right = NULL;
}
};
class treePersons
{
protected:
public:
Node *root;
treePersons(){
root = NULL;
}
int fileName(Person *data[])
{
ifstream fin;
fin.open ("dbfile1.txt");
if (!fin.is_open())
cout << "File not found" << endl;
int i;
for(i = 0; i<100; i++)
while(fin.good())
{
fin >> data[i]->social >> data[i]->birthday >> data[i]->first >> data[i]->last >> data[i]->state >> data[i]->balance;
i++;
}
return i;
}
void add(Person *data[], Node*root)
{
int i = fileName(data);
if(root == NULL)
{
root = new Node();
}
for(int l = 0; l<i; l++)
{
if(data[i]->last == root->data.last)
{
if(data[i]->first != root->data.first)
{
if(data[i]->first < root->data.first)
{
add(data, root->left);
}
else if(data[i]->first > root->data.first)
{
add(data, root->right);
}
else if(data[i]->last == root->data.last && data[i]->first == root ->data.first)
{
cout << "already exists" << endl;
}
else if(data[i]->first < root->data.first)
{
add(data, root->left);
}
else if(data[i]->first > root->data.first)
{
add(data, root->right);
}
}
}
}
}
void printAlphabetically(Node *root)
{
if (root != NULL)
{
printAlphabetically(root->left);
cout << root->data.last << endl;
printAlphabetically(root->right);
}
return;
}
void display(Person *data[],Node *root)
{
add(data,root);
printAlphabetically(root);
};
};
struct State{
string state;
Person data;
State* left;
State * right;
State();
State(Person x)
{
data = x;
left = NULL;
right = NULL;
}
};
class treeState{
protected:
State *root;
public:
treeState()
{
root = NULL;
}
};
void main(){
treePersons T;
T.display(T.root->data,T.root);
}

Answer 1

It's very simple to see what's wrong with your code. You have the following:
treePersons T;
T.display(T.root->data, T.root);
Let's have a look at what a treePersons is:
class treePersons
{
Node *root;
...
};
It contains a single member: a Node. A Node is:
struct Node
{
Person data;
Node *left;
Node *right;
...
};
Your treePersons::display() function has the following signature:
void display(Person *data[], Node *root)
And you are passing a t.root->data (a Person) and t.root (a Node*)
The problem is you are attempting to pass a Person as a Person*[] which just isn't going to happen. There's no way to make that Person into a Person[], and you probably meant to make display take a Person* pointer, which will allow you pass a single Person or a container of Person: void display(Person* data, Node* root);
Of course, doing so will lead you down a big trail of problems as #R Sahu pointed out in the comments (most of your functions take a Person*[]. The solution here is to rethink what you are doing, and as #R Sahu suggests start much smaller and build up your program from there.
Consider also using std::vector when you need containers, and std::unique_ptr or std::shared_ptr where you require pointers (otherwise just use objects!). Also read (really read) the compiler output. It's telling you what the problem is, you just need to read.