Linked Lists in C

Okay, took the time to look at the spec for how that should behave so I can get the signs right >_>
p < q: -1
p = q: 0
p > q: 1

Code:

compare (*p, *q) {
  if (p == null) return -1;
  if (q == null) return 1;
  // or vice versa
  if (p->next != null && q -> next != null) {
   c = compare(p->next, q->next)
   if (c == 0) {
    if (p > q) return 1;
    if (q > p) return -1;
    else return 0;
   }
   else return c;
  }
  else return 0;
}

Since it's recursive it goes through from the most significant digit, so for example 4000 vs 5555
p = null & q = null -> return 0
p = 4, q = 5, c = 0 -> return -1
p = 0, q = 5, c = -1 -> return c = -1 (repeat x3)
return -1

Since 4000 < 5555 this seems to be returning the correct value of -1.



Whereas your code,

Code:

int compare(struct integer *p, struct integer *q)
{
    
    int j;
    
    while  (p != NULL){
           if(q==NULL){
             return 1;}
             else if (q!=NULL){
                          if (p>q){
                                   j=1;}
                          else if (p<q){
                                   j= -1;}
                          else if (p==q){
                                   j= 0;}
                                   }
             p= p->next;
             q= q->next;
            
            
             }
            
            
return (j);            
}

again, 4000 vs. 5555
p=0, q=5 -> j = -1 (repeat x3)
p=4, q=5 -> j = -1
now p == null so it should break out of the while loop and return j=-1.

I'm not sure what you have differently but this seems like it would work correctly?