Help needed in understanding one line;

Question

Here's some part of the code

class Node {
public:
int data;
Node * next;
};

void push(struct Node ** head_ref, int new_data) {
struct Node * new_node = (struct Node * ) malloc(sizeof(struct Node));
new_node->data = new_data;
new_node->next = ( * head_ref);
( * head_ref) = new_node;
}

In this code I didn't get the meaning of "struct Node ** head_ref" (parameter of the push function)

why we need the struct keyword when there's already the Node data type.

Answer 1

In the push function you are declaring a new variable, so even if you have another Node data type it doesn't count here unless it is a global variable. It's just like int new_data , here even if you have another new_data somewhere you should use int keyword because for this push function it is a new variable and you must declare the data type.

While declaring a structure data type you should use struct keyword for every new variable or you can use typedef keyword.