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Linked list. Accessing data in element inside node.

shrayder (21)
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In my class Car. I have this

ID Model Driver
1  Car   John

If im using the default print() function from the Linked List, it will show all of em

ID Model Driver
1  Car   John

What I want it to show is only the driver

ID Driver
1  John

What should I write to retrieve the driver only?


2)
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I want the change the driver data into something else

ID Model Driver
1  Car   John
Insert new driver: Popo

ID Model Driver
1  Car   Popo
Driver changed!

What should I write to change the driver without having 
to reconstruct the whole element inside the node?



Here's the sample of the code
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Class Car(){
 ....
 friend ostream& operator<< (ostream& os, Car& c) {
  os << left << c.getModel();
  os << left << c.getDriver();
  return os;
  }
 friend istream& operator>> (istream& is, Car& c){
  is >> model;
  is >> driver;
  return is;
 }
};

template <typename T>
struct Node {
 .....
};

template <typename T>
class LList {
 .....
 void print() {
   Node<T> *ptr = start;
   int i=0;
   while (ptr!=NULL ) {
    cout << "\t" << ++i << ". " << ptr->info;
    ptr = ptr->next;
    }
   }   
};

int main(){
 LList<Car> cars;
 Car c("Car", "John");
 cars.insertBack(c);
 cars.print();
 system("pause");
 return 0;
}


Are those possible? Thanks!
Last edited on
keskiverto (10402)
Possible, yes.

1. Your LList::print could take a function pointer with 0 as default. If pointer is 0, you print as you do now. If pointer is not 0, then you call the function with the ptr->info as parameter.

2. You LList must have a method to reference single node, and the node type must allow change of member.
shrayder (21)
Thanks for the reply.

Talking about referencing single node. I've wrote this if it's what you're refering from
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void insertAt (T& elementToInsert, int atIndex) {
    int i = 1;
    Node<T> *ptr = start;
    Node<T> *newNode = new Node<T>;
    while(ptr != NULL && i != atIndex)
        if(i != atIndex)
        {
            ptr = ptr->next;
            i++;
        }
        if(i == atIndex)
            newNode->info = elementToInsert;
            newNode->next = ptr->next;
            ptr->next = newNode;
    }


And I rephrase my question.

how to retrieve member of element inside node?
how to write the code. I don't have any clue of doing it
Last edited on
keskiverto (10402)
See http://www.cplusplus.com/reference/forward_list/forward_list/front/
Do you notice, that the front() returns a reference to value_type object?

The front() is just an alternative for *(begin()). Begin returns iterator. Iterator can advance to point other elements, but then dereference would return reference to that further object.

You could consider a LList member
T& itemAt (int atIndex) const;

PS. If the user gives an invalid atIndex, then your insertAt will crash.
Last edited on
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