Sorted Insertion in linked list - c

Question

I'm trying to create a function that does sorted insertion based on two variables, level and name. Apparently I'm having some logic and syntax errors.
My linked list structure:
struct node {
struct node *next;
int level;
char name;
};
My string compare function:
int compare(struct node *one, struct node *two)
{
return strcmp(one->name, two->name);
}
My insertion function:
void insert(struct node **head, const int level, const char name, int(*cmp)(struct node *l, struct node *r))
{
struct node *new =NULL;
/* Find the insertion point */
for (; *head; head = &(*head)->next)
{
if ((*head)->level > level) { // I think this is what is causing the issue
if (compare(*head, new) > 0)
break;
}
}
new = malloc(sizeof *new);
new->level = level;
new->name = name;
new->next = *head;
*head = new;
}
and this is the call stack:
insert(node **head, const int level, const char name, int(*)(node *, node *))

Answer 1

Your syntax error is this line:
return strcmp(one->name, two->name);
The function strcmp expect two char* (aka char pointers) but you give it two char.
The problem is... Do you want
char name;
or
char* name;
That is important in order to get compare right.
Further you need to rearrange your insert function so that you create the new node before using it. Something like:
void insert(struct node **head, const int level, const char name, int(*cmp)(struct node *l, struct node *r))
{
struct node *new =NULL;
// Create and initialize new....
new = malloc(sizeof *new);
new->level = level;
new->name = name;
/* Find the insertion point */
for (; *head; head = &(*head)->next)
{
if ((*head)->level > level) { // I think this is what is causing the issue
if (cmp(*head, new) > 0)
// ^^^ So that you can use it here
break;
}
}
new->next = *head;
*head = new;
}

Answer 2

You are passing a NULL value to the cmp function (?!? probably the correct function is int compare(...). Try to initialize the value of the new variable before to pass it to the function.

Answer 3

You declare node.name to be of type char, but your comparison function is written as if they were null-terminated arrays of char or pointers into such arrays (i.e. C strings). You appear to want this:
struct node {
struct node *next;
int level;
char *name;
};
or maybe this:
struct node {
struct node *next;
int level;
char name[MY_MAXIMUM_NAME_LENGTH_PLUS_ONE];
};
Furthermore, your insert() function passes a NULL pointer to the comparison function as its second argument, because you never allocate any memory for pointer new, and, of course, never assign values to the non-existent members. That doesn't even make sense. What do you think you're comparing to? You seem to want something like this:
struct node *new = malloc(sizeof *new);
if (!new) {
// allocation failure -- abort ...
}
new->level = level;
new->name = /* hmmmm ... */;
Of course, the problem with the type of your names crops up here, too.