Linked list program in C hangs - c

Question

I am writing a linked list program
to add items and display those items.
I am able to add first item successfully,
but error occurs while adding the second item.
I tried to figure out the error,but
everything looks fine to me.
The program hangs,here is my code:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
struct link_list
{
int number;
struct link_list *next;
};
typedef struct link_list node;
node *head;
void add(int num)
{
node *newnode,*current;
newnode = (node *)malloc(sizeof(node));
newnode->number = num;
newnode->next = NULL;
if(head == NULL)
{
head = newnode;
current = newnode;
}
else
{
current->next = newnode;
current = newnode;
}
}
void display(node *list)
{
list = head;
if(list == NULL)
{
return;
}
while(list != NULL)
{
printf("%d",list->number);
list = list -> next;
}
printf("\n");
}
int main()
{
int i,num;
node *n;
head=NULL;
while(1)
{
printf("\nList Operations\n");
printf("===============\n");
printf("1.Insert\n");
printf("2.Display\n");
printf("3.Exit\n");
printf("Enter your choice : ");
if(scanf("%d",&i)<=0)
{
printf("Enter only an Integer\n");
exit(0);
}
else
{
switch(i)
{
case 1:
printf("Enter the number to insert : ");
scanf("%d",&num);
add(num);
break;
case 2:
if(head==NULL)
{
printf("List is Empty\n");
}
else
{
printf("Element(s) in the list are : ");
}
display(n);
break;
case 3: return 0;
default: printf("Invalid option\n");
}
}
}
return 0;
}

Answer 1

The issue is with the value of current not persisting across function calls. Either move it outside of the function (i.e. right below the head declaration), or declare it as static.

Answer 2

just one change , define your current pointer outside the scope of void add
node *head,*current;
here is the correct code
struct link_list
{
int number;
struct link_list *next;
};
typedef struct link_list node;
node *head,*current;
void add(int num)
{
node *newnode;
newnode = (node *)malloc(sizeof(node));
newnode->number = num;
newnode->next = NULL;
if(head == NULL)
{
head = newnode;
current = newnode;
}
else
{
current->next = newnode;
current = newnode;
}
}