Question

I have a function which is supposed to take two linked lists and put them together.

    void Append(struct node** aRef, struct node** bRef){
     struct node* first = *aRef;
     struct node* second = *bRef;
     struct node* temp = NULL;

    while(first != NULL || second != NULL){
          Push(&temp, first->data);
          Push(&temp, second->data);
          first = first->next;
          second = second->next;
     }

     *aRef = temp;
     DeleteList(&second);
}

I want to sort it but I keep getting a segmentation fault when I replace the while loop with this :

while(first != NULL || second != NULL){
      if(first->data < second->data){
           Push(&temp, first->data);
           first = first->next;
      }
      else{
           Push(&temp, second->data);
           second = second->next;
      }
 }

The Push() function just adds some data to a struct node:

void Push(struct node** headRef, int data){
     struct node* new = malloc(sizeof(struct node));
     new->data = data;
     new->next = *headRef;
     *headRef = new;
}

struct node{
     int data;
     struct node* next;
};

Answer 1

This solves your problem. Because if you dot not test both, you can not perform the first comparation.

while(first != NULL || second != NULL){
      if((first != NULL && second != NULL && first->data < second->data) || (first != NULL && second == NULL)){
           Push(&temp, first->data);
           first = first->next;
      }
      else if (second != NULL) {
           Push(&temp, second->data);
           second = second->next;
      }
 }