Not able to write information into linear linked list - c

Question

The processFilefunction scans the information from the file correctly to p, however the addNodeLast function doesn't add the information from p to the linked list employees because it crashes.
Can someone help me fix the crashing, so that it will link each node together?
#include <stdio.h>
#include <stdlib.h>
#include "list.h"
void processFile(NODEPTR *employees, FILE *fp);
void outputPayFile(NODEPTR employees);
FILE *fp;
int main(void) {
NODEPTR employees;
if (fopen_s(&fp, "payfile2.txt", "r") != 0) {
printf("Failed to open payfile.txt for reading\n");
exit(0);
}
...missing code...
}
void processFile(NODEPTR *employees, FILE *fp) {
int i = 0;
NODEPTR p;
while(i < 5) {
printf("Entered Loop\n");
p = (NODEPTR) malloc(sizeof(node));
fscanf(fp, "%s %s %c %d %c %f\n", p->firstName, p->lastName, &(p->gender),
&(p->tenure), &(p->rate), &(p->rate), &(p->salary));
addNodeLast(employees, p);
i++;
}
}
In list.h:
void addNodeLast(NODEPTR *list, NODEPTR t) {
NODEPTR p;
if (*list == NULL)
*list = t;
else {
p = *list;
while (p->next)
p = p->next;
p->next = t;
}
}
Definition of NODEPTR:
typedef struct node {
char firstName[11];
char lastName[16];
char gender;
int tenure;
char rate;
float salary;
struct node *next;
} node, *NODEPTR;

Answer 1

You never initialise the next pointer. This is a common mistake. The call to malloc does not zero your memory. As a result, when you add a node to a non-empty list, you are likely to run straight off the end because the first node's next pointer could be non-null.
You need to at least do this:
p = malloc(sizeof(node));
if( p != NULL ) p->next = NULL;
You could consider using calloc, which does zero:
p = calloc(1, sizeof(node));