Struct pointer compatibility

Question

Suppose we have two structs:

typedef struct Struct1
{
    short a_short;
    int id;
} Struct1;

typedef struct Struct2
{
    short a_short;
    int id;
             


        

Answer 1

It is safe, as far as I know.

But it's far better, if possible, to do:

typedef struct {
    Struct1 struct1;
    short another_short;
} Struct2;

Then you've even told the compiler that Struct2 starts with an instance of Struct1, and since a pointer to a struct always points at its first member, you're safe to treat a Struct2 * as a Struct1 *.