Passing argument from incompatible pointer type warning

Question

I\'ve been trying to figure out pointers in C most of today, even asked a question earlier, but now I\'m stuck on something else. I\'ve got the following code:

Answer 1

You're getting confused because of multiple typedefs. LIST is a type representing a pointer to struct listhead. So, you want your ListCreate function to return a LIST, not a LIST *:

LIST ListCreate(void)

The above says: ListCreate() function will return a pointer to a new list's head if it can.

Then you need to change the return statement in the function definition from return &headpoolp-1; to return headpoolp-1;. This is because you want to return the last available head pointer, and you have just incremented headpoolp. So now you want to subtract 1 from it and return that.

Finally, your main() needs to be update to reflect the above changes:

int main(void)
{
    /* Make a new LIST */
    LIST newlist;  /* a pointer */
    newlist = ListCreate();
    int i = ListCount(newlist);
    printf("%d\n", i);
    return 0;
}