Linked List

#include<stdio.h>
#include<stdlib.h>
#include<stdbool.h>

struct test_struct
{
int val;
struct test_struct * next ;
};

struct test_struct * head = NULL;
struct test_struct * curr = NULL;


struct test_struct * create_list( int val )
{
struct test_struct * ptr = (struct test_struct*) malloc( sizeof (struct test_struct ));

if ( NULL == ptr )
        {
printf("\n Node creation failed ");
return NULL;
        }
ptr -> val = val;
ptr -> next = NULL;

head = curr = ptr;
return ptr;
}

struct test_struct * add_list(int val, bool add_to_end )
{
if ( NULL == head )
{
head = create_list(val);
return head;
}

struct test_struct * ptr = ( struct test_struct *)malloc( sizeof(struct test_struct ));
 
if ( ptr == NULL )
{
printf("\n  node  failed ");
return NULL;
}


ptr -> val = val;
ptr -> next = NULL;

if( add_to_end )
{
curr -> next = ptr;
curr = ptr;
}
else
{
ptr -> next = head;
head = ptr;
}
return ptr;
}

void print_list ()
{
struct test_struct * ptr = head;
        printf("\n\n Printing the list ");
while ( ptr != NULL )
{
printf("\n  %d ", ptr->val);
ptr = ptr-> next;
}
}

int main()
{
int i=0, ret = 0;
struct test_struct * ptr = NULL;

//print_list();
printf("\n Adding to list ");
  for ( i = 10; i< 20; i++)
add_list(i, true);
 
print_list();

printf("\n Adding to list ");
  for ( i = 0 ; i< 30; i++)
add_list(i, false );

print_list();
}