Thread: how to add codes ?

s.c

Code:

#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
//#define NULL 0
#define LEN sizeof(struct student)
struct student
{
       long num;
       float score;
       struct student * next;
};
int n;

struct student *create(void)
{
       struct student *head;
       struct student *p1,*p2;
       n = 0;
       p1 = p2 = (struct student *) malloc(LEN);
       scanf("%ld,%f",&p1->num,&p1->score);
       head = NULL;
       while(p1->num != 0)
       {
                     n++;
                     if ( n == 1 ) head = p1;
                     else p2->next = p1;
                     p2 = p1;
                     p1 = (struct student *) malloc (LEN);
                     scanf("%ld,%f",&p1->num,&p1->score);
       }
       p2->next = NULL;
       return(head);
}

void showLink(struct student *h)
{
     while( h->num != 0 )
     {
            printf("%ld,%f\n",h->num,h->score);
            h = h->next;//if h now is pointng the last node, h->next is invalid, then error occurs
     
     }
}
int main()
{
    struct student *h;
    h = create();
    showLink(h);
    return 1;
}

h = h->next;//if h now is pointng the last node, h->next is invalid, then error occurs

how to add codes to solve this problem?

Instead of:

Code:

while( h->num != 0 )

Go with:

Code:

while(h)

This way, when you do h = h->next, if h becomes a null pointer, the loop will end.

OK, thanks