C++ – Print Function Linked Lists C++

cfunctionlinked listprinting

I'm currently learning Linked Lists in C++, and I can't write a print function which prints out the elements of the list; I mean I wrote the function but it doesn't work properly.

#include <iostream>

using namespace std;

struct node
{
    char name[20];
    node* next;
};

node* addNewPerson(node* head)
{
    node* person = new node;

    cout << "Name: ";
    cin >> person->name;

    person->next = NULL;

    if (head == NULL) //is empty
    {
        head = person;
    }

    else
    {
        person = person->next;
    }

    return head;
}

void printList(node* head)
{
    node* temp = head;

    cout << temp->name << endl;
}

int main()
{
    node* head = NULL;

    node* temp = head;

    unsigned short people = 0;

    cout << "How many people do you want to invite to the party?" << endl;
    cout << "Answer: ";
    cin >> people;

    cout << endl;

    for (unsigned short i = 1; i <= people; i++)
    {
        addNewPerson(head);

        cout << endl;
    }

    cout << "LIST: " << endl;
    cout << endl;

    while (temp != NULL)
    {
        printList(temp);
        temp = temp->next;
    }

    cin.get();
}

I am wondering what I'm doing wrong, please help me!

Best Answer

It is obvious that function addNewPerson is wrong.

node* addNewPerson(node* head)
{
    node* person = new node;

    cout << "Name: ";
    cin >> person->name;

    person->next = NULL;

    if (head == NULL) //is empty
    {
        head = person;
    }

    else
    {
        person = person->next;
    }

    return head;
}

You allocated new node person. 

    node* person = new node;

Set its field next to NULL

    person->next = NULL;

Then if head is not equal to NULL you set person to person->next

        person = person->next;

As person->next was set to NULL it means that now also person will be equal to NULL.

Moreover the function returns head that can be changed in the function. However you ignore returned value in main

addNewPerson(head);

At least there should be

head = addNewPerson(head);

The valid function addNewPerson could look the following way

node* addNewPerson(node* head)
{
    node* person = new node;

    cout << "Name: ";
    cin >> person->name;

    person->next = head;
    head = person;

    return head;
}

And in main you have to write

  for (unsigned short i = 1; i <= people; i++)
  {
    head = addNewPerson(head);

    cout << endl;
  }

Function printList does not output the whole list. It outputs only data member name of the first node that is of head. 

void printList(node* head)
{
    node* temp = head;

    cout << temp->name << endl;
}

It should look the following way

void printList(node* head)
{
  for ( ; head; head = head->next )
  {
    cout << head->name << endl;
  }
}

And at last main should look as

int main()
{
    node* head = NULL;

    unsigned short people = 0;

    cout << "How many people do you want to invite to the party?" << endl;
    cout << "Answer: ";
    cin >> people;

    cout << endl;

    for ( unsigned short i = 0; i < people; i++ )
    {
        head = addNewPerson(head);

        cout << endl;
    }

    cout << "LIST: " << endl;
    cout << endl;

    printList( head );

    cin.get();
}
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