分配给结构的不兼容指针类型

Question

I'm just trying to make some kind of pointer to "Nall" struct so I wrote this code

Nall **headall;
    headall = malloc (30000 * sizeof (Nall));
    for (i = 0; i < 30000; i++) {
        *(headall+i) = newNall;
    }

and now I get this error

"warning: incompatible pointer types assigning to Nall * (aka struct nodeall * ) from Nall *(void) (aka struct nodeall *(void) ) [-Wincompatible-pointer-types] *(headall+i) = newNall; "

Answer 1

From the compiler warning I'm assuming that newNall is actually a function that allocates a new struct nodeall and returns a pointer to it. In that case, your code should look like this:

Nall **headall;
headall = malloc(30000 * sizeof *headall);
for (i = 0; i < 30000; i++)
  headall[i] = newNall();

Note the argument to the sizeof operator, and the parentheses after newNall .