Cannot access memory at address at address "" (gdb) - c

Question

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
struct Node {
/* Data fields with appropraiate types */
char fname[64];
char lname[64];
char puid[16];
int Age;
struct Node *next;
};
struct List {
struct Node *start;
int numNodes;
};
struct List * initialize_list() {
struct List *list = (struct List *) malloc(sizeof(struct List *));
list -> numNodes = 0;
list -> start = (struct Node *) malloc(sizeof (struct Node *));
return list;
}
struct List * CreateList() {
struct List *list = initialize_list();
return list;
}
void Traverse(struct List *list) {
struct Node *node = (struct Node *) malloc (sizeof(struct Node));
int i = 1;
node = list -> start -> next;
while (node != NULL) {
printf ("\nNode: %d", i);
printf("\nPUID: %s", node -> puid);
node = node -> next;
i++;
}
if (i == 1) {
printf("\n\nEmpty List");
}
}
struct Node *CreateNode(char first_name[], char last_name[], char PUID[], int age) {
struct Node *newNode = (struct Node *) malloc (sizeof(struct Node *));
strcpy(newNode->fname, first_name);
strcpy(newNode->lname, last_name);
strcpy(newNode->puid, PUID);
newNode->Age = age;
newNode->next = NULL;
return newNode;
}
void InsertFront(struct List *list, char first_name[], char last_name[], char PUID[], int age) {
struct Node *newNode = CreateNode (first_name, last_name, PUID, age);
if (list -> numNodes == 0) {
list -> start -> next = newNode;
list -> numNodes++;
return;
}
newNode -> next = list -> start -> next;
list -> start -> next = newNode -> next;
list -> numNodes++;
return;
}
int main () {
struct List *myList = CreateList();
while (1) {
int option = 0;
char fname[64];
char lname[64];
char puid[16];
int age;
printf("\n0. Exit Program \n1. Insert Front\n2. Insert Middle\n3. Insert End\n4. Delete Front\n5. Delete Middle\n6. Delete End\n7. Traverse \n8. Look Up by Index\n");
printf ("Enter option: ");
option = getchar();
if (option == '0') {
exit (0);
}
else if (option == '1' || option == '2' || option == '3') {
printf("Enter first name: ");
scanf("%s", fname);
printf("Enter last name: ");
scanf("%s", lname);
printf("Enter PUID: ");
scanf("%s", puid);
printf("Enter age: ");
scanf("%d", &age);
if (option == '1') {
InsertFront (myList, fname, lname, puid, age);
}
else if (option == '2') {
int index;
printf ("Enter position to Insert: ");
scanf ("%d", &index);
InsertMiddle (myList, index, fname, lname, puid, age);
}
else if (option == '3') {
InsertEnd (myList, fname, lname, puid, age);
}
}
else if (option == 4) {
}
else if (option == 5) {
}
else if (option == 6) {
}
else if (option == '7') {
Traverse (myList);
}
else if (option == 8) {
}
else {
}
getchar();
}
return 0;
}
I'm relearning some of this but I'm not sure where I'm going wrong.
I get a segmentation fault when the program reaches the Traverse() function.
I can access the Node that before the iteration of the while loop is not complete. As soon as the next iteration begins the myList -> start -> next can't be accessed any longer.

Answer 1

In Create node method:
malloc (sizeof(struct Node *))
Will allocate only 4 or 8 bytes because it sizeof pointer.
It should be:
malloc (sizeof( Node ))
to allocate space for an object