Question

Why would I want to do this?

typedef struct Frame_s
{
int x;
int y;
int z;
} Frame_t;

Also if I want to create an object what do I use Frame_s or Frame_t?

Answer 1

You would use Frame_t.

With typedef you are saying that Frame_t and struct Frame_s are the exact same type.

So these are equivalent sentences:

// 1
Frame_t f;

// 2
struct Frame_s f;

I would use:

typedef struct
{
   int x;
   int y;
   int z;
} Frame_t;

And always declare my vars like this:

Frame_t f1, f2, f3;

Confusion usually comes from places where you use that sentence in a C++ piece of code. If you use C++ with that typedef you can use either:

// 1
Frame_t f;

// 2
Frame_s f;

But if you use a plain C compiler, then //2 is invalid.