Thread: linked list search

Hello, I read an article on linked list here: C Linked List Data Structure Explained with an Example C Program

Code:

struct test_struct* search_in_list(int val, struct test_struct **prev)
{
    struct test_struct *ptr = head;
    struct test_struct *tmp = NULL;
    bool found = false;
    
    printf("\n Searching the list for value [%d] \n",val);
    
    while(ptr != NULL)
    {
        if(ptr->val == val)
        {
            found = true;
            break;
        }
        else
        {
            tmp = ptr; 
            ptr = ptr->next;
        }
    }
    
    if(true == found)
    {
        if(prev)
            *prev = tmp;
        return ptr;
    }
    else
    {
        return NULL;
    }
}


......
........
struct test_struct *prev = NULL;
    struct test_struct *del = NULL;
    
    printf("\n Deleting value [%d] from list\n",val);
    
    del = search_in_list(val,&prev);

What is "if(prev)"? Wouldn't "prev" always have the same value? Secondly, if tmp is NULL (which will be the case when the loop if(ptr->val == val) finds a match the first time it is run), is *prev assigned a NULL?