Thread: Problem with nodes

Good day guys!
I am an IT student currently learning linked list. I have a problem with my code here. After I call addFront() my list doesn't change when I display it. How do I somewhat change/fill my list without changing the function type? I know it works on pointers still messed up with linked list.




list.h

Code:

typedef struct node *nodeptr; 

struct node{
int item;
nodeptr next;
};

typedef nodeptr List;

void addFront(List head, int item);
void display(List list);

list.c

Code:

#include<stdio.h>
#include<stdlib.h>
#include"list.h"

void addFront(List head, int item){
List temp;
temp = (List)malloc(sizeof(List));
temp->item = item;
temp->next=head;
head=temp;
}

void display(List list){
List ptr=list;
while(ptr!=NULL){
printf("%d ", ptr->item);
ptr=ptr->next;
}
}

main.c

Code:

#include<stdio.h>
#include<stdlib.h>
#include"list.h"

int main(){
List head=NULL;
addFront(head, 5);
display(head);
}

> head=temp;
You're modifying head, but main doesn't see that happen.

Try
List addFront(List head, int item)
where you return the (possibly new) head each time you change a list in some way.

And you do this in main
head = addFront(head, 5);

actually this problem was our seatwork earlier. Our teacher gave us void addFront(List head, int item) and said not to change it. I actually did that too. Wonder if it's even possible with void.

Your only other option in C is make head a pointer,

void addFront(List *head, int item)

Which is called with
addFront(&head, 5);

If you can't do either of those things, you're stuck (without using f-ugly globals).