CODEWITHSUNDEEP
c++pointerslinked-list
Rishu Agrawal
Rishu Agrawal

Reputation: 167

Allocating new node in Linked List using C++ reference parameters

This code snippet is valid for creating new node at the begining. 

void push(node **head_ref,int n_data){
   node *new_node= new(node);
   new_node->data=n_data;
   new_node->next=(*head_ref);
   *head_ref=new_node;
}
int main(){
   node *head=NULL;
   push(&head,data);
   return 0;
}

This is invalid but why? What i am trying to do is create a reference parameter as mentioned in Herbert Schildt.

void push(node &(*head_ref),int n_data){
   node *new_node= new(node);
   new_node->data=n_data;
   new_node->next=head_ref;
   head_ref=new_node;
}
int main(){
   node *head=NULL;
   push(head,data);
   return 0;
}

Upvotes: 0

Views: 981

Answers (2)

byteunit
byteunit

Reputation: 1063

A Null-Pointer can't be a reference! So in C++ there is the only way, to use a double pointer.

Using a Reference to a Null-Pointer could lead to undefined behavior, this means that you should avoid this.

Maybe boost::optional is what you need, but than you need some modifications.

But why are you not just using the std::list?

Upvotes: 0

Some programmer dude
Some programmer dude

Reputation: 409186

The declaration node &(*head_ref) makes head_ref a pointer to a reference, not a reference to a pointer, which would be node*& head_ref.

Upvotes: 2

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