C 数据结构，变量

Question

Sorry for noob question

I have a struct:

typedef struct  s_test
{
    int         head;
    char        *end;
}               t_test;

My code:

int main()
{
   t_test a;
   t_test *b;
}

What is different between a.head and b->head ?. Why can't I type a->head or b.head ?. I know b is a pointer which holds an address of a variable type t_test .

Answer 1

Doing b->head is just convenient syntactic sugar for doing (*b).head .

You have to dereference a pointer to a struct before you can use the dot notation on it, that's why you cannot do b.head .

The reason why you cannot do a->head is that a is not a pointer, so it cannot be dereferenced. The dereferencing operator * only makes sense for pointers.