# include <iostream>
// #include <string> 
// #include <cmath>
// #include <cstdlib>
// #include <iomanip>
// #include <fstream>
// #include <vector>
using namespace std;
#define NN 1000
const int MAXHASH = 100000;

class person {
public:
	int ID;
	char name [25];
	int age;
	char* address;
	int phone;
	
	person* next;
	person* prev;
};





int myhash_function(char s[]){
	int sum=0,i=0,v;
//	cout<<"\n hash("<<s<<"):\n";
	while(s[i]>0){
		i++;
		v = s[i] * i*i;
		sum += v;
//		cout << "        "<< i <<"  "<< s[i-1]<<"  "<<v<<"   "<< sum<< endl;
	}
	int sumret  = sum % MAXHASH;
//	cout <<sum<<" % "<< MAXHASH << " = "<<sumret <<endl<<endl;
	return sumret;
}

person* GiveMeElement(char* somename, person** head){ //returns the pointer to existing entry; if not exists creates one with count 0

	if (*head==0){ //create a list first object here
			cout<<"	GiveMeElement: name="<<somename<<"  create new listhead\n";
			person* f= new person;
			f->next=NULL;
			f->prev=NULL;
			strcpy(f->name, somename);
			f->ID = 0;
			f->age=0;
			*head = f;
			return f; 		
	}
	person* e = *head;
	while (strcmp (e->name, somename) !=0){ //look for the word or for the end of the list
		if (e->next==NULL){ //create the new entry here, must return
			cout<<"   	GiveMeElement: name="<<somename<<"   create entry in existing list\n";
			person* f= new person;
			f->next=NULL;
			e->next=f;
			f->prev=e;
			strcpy(f->name, somename);
			f->ID = 0;
			f->age=0;
			return f; 		
		}
		e=e->next;
	}
	cout<<"\n   GiveMeElement: name="<<somename<<"  found entry at address="<<e<<"\n";
	return e;
}






//function with struct param
void display_person(person t, char* message){
	cout << message <<t.ID<<"  name="<<t.name<<"  phone="<<t.phone;
	cout<<"  age="<<t.age<<"  address="<<t.address<<" "<<endl;//(void*)t.address <<endl;	
	t.age=50;
}

//function with pointer-to-struct param
void display_person_2(person* t, char* message){
	cout << message <<t->ID<<"  name="<<t->name<<"  phone="<<t->phone;
	cout<<"  age="<<t->age<<"  address="<<t->address<<endl;	
	(*t).age=50;
}
void ListAllPeople (person* head){
	cout<<"\nListing all people in the list at head="<<head<<":\n";
	person * t= head;
	while (t!=NULL){
		display_person_2(t, "     ");
		t=t->next;
	}
}

int main(){
	
	person x;
	x.ID=1;
	x.age=35;
	strcpy(x.name, "Virgil");

//VERY WRONG, not allocated
//	strcpy(x.address,"Huntington Ave");

	char add [] = "Huntington Ave"; 
	x.address = add;
	
	x.phone = 123456789;
	
	cout<<"\n\nUSING STRUCTURES\n display first: "<<x.ID<<" "<<x.name<<" "<<x.phone<<endl;
	display_person (x, "\n displayed second with a function:\n");
	cout<< "sizeof(person)="<<sizeof(person)<<endl;
//return 0;
	
	
//ARRAYS OF STRUCTURE
	person A[10]; // how much memory ?
	A[0]=x;
	A[0].age=30;
	strcpy(A[0].name, "Pavlu");
	strcpy(A[0].address, "Boston MA 02115");
	display_person(A[0], "\nthis is A[0]:\n");
//return 0;

	A[1].ID=13;
	A[1].age=24;
	A[1].phone = 6171234567;
	strcpy(A[1].name, "Alice");
	A[1].address = new char[20];
	strcpy(A[1].address, "Somerville MA");
	display_person(A[1], "\nthis is A[1]:\n");
	
	
	display_person(x, "\n\n\nthis is x again: \n"); cout<<endl;
	display_person_2 (&x, "display x with a pointer function:\n");
//return 0;



	person *y = new person;
	(*y).ID=12;
	y->age=22;
	strcpy(y->name, "John Smith");
	char addy []= "Washington DC"; y->address = addy;
	y->phone = 1110002222;
	display_person_2 (y, "\ndisplay y with a pointer function:\n");
//return 0;



///////////////////// LINKED LISTS ////////////////
	cout<<"\n\n\n\n LINKED LISTS\n";
	person *z = new person;
	z->ID=3;
	z->age=25;
	strcpy(z->name, "Alice Dee");
	char addz []= "New York"; z->address = addz;
	z->phone = 999000333;
	display_person_2 (z, "\ndisplayed z with a pointer function:\n");
	y->next=z; //manual
	z->prev=y;
	x.next=y;
	y->prev=&x;
	
//return 0 ;

	person* listhead1 = &x;
	person* t = GiveMeElement ("Lisa Smith", &listhead1);
	t->age =39;
	t->ID=5;
	t->address = "San Francisco, CA"; //exercise: what happens here?

 	t = GiveMeElement ("Terry Boyle", &listhead1);
	t->age =24;
	t->ID=7;
	t->address = "Miami, FL";
	
		ListAllPeople(listhead1); cout<<endl;
//return 0;
	
	person* listhead2 = NULL;
	t = GiveMeElement ("The Iron lady", &listhead2);
	t->age = 80;
	t->ID=1;
	t->address = "London, UK";

	t = GiveMeElement ("Tony Blair", &listhead1);
	t->age = 61;
	t->ID=2;
	t->address = "London, UK";

	t = GiveMeElement ("Winston Churchill", &listhead2);
	t->age = 132;
	t->ID=3;
	t->address = "Woodstock UK";



	ListAllPeople(listhead1); cout<<endl;
	ListAllPeople(listhead2); cout<<endl;
return 0;








}