typedef a struct before it's declared

Question

I\'m not a beginner, I\'m very familiar with the following idiom:

typedef struct Foo_ Foo;// I know typedef struct Foo Foo is fine, I\'m just trying to make          


        

Answer 1

Under certain circumstances, it is valid to use a struct ... type before it is declared. It is a so-called "incomplete type" then.

For example, it is valid to declare a variable as a pointer to an "incomplete" struct, as well as (as you can see) a typedef.