C中的Typedef和struct

Question

Is there any difference between those two:

typedef struct ddwq{
    int b;
}ta;

typedef struct {
    int b;
}ta;

Answer 1

In the former case, you can reference the type of the struct as either struct ddwq or ta . In the latter case, you can only reference it as ta since the struct has no tag.

The first case is required if the struct will contain a pointer to itself such as:

typedef struct ddwq{
    int b;
    struct ddwq *p;
}ta;

The type name ta isn't visible inside of the struct, so the struct must have a tag name for it to reference itself.