c - Why I can pass a pointer in a method and "free" the memory inside?

Question

I have always read that in order to modify any variable inside a function in C, you must pass a pointer to that variable.

If I want to delete a particular element in a linked list, and I do something like:

int DeleteElement(element **head, element *deleteMe)
{
  free(deleteMe);
  return 1;
}

Why am I able to free that deleteMe and that gets reflected outside the DeleteElement function? Isn't the deleteMe another thing inside the function?

Thanks

Answer 1

您没有向指针写入任何内容deleteMe。您正在使用它（以只读方式）来确定要释放的对象（它指向的对象）。

Answer 2

您将指针传递给地址（用于提供该指针的名称或变量无关紧要）。该地址的内存块被释放。因此，它也在DeleteElement函数“外部”被释放。