Declaring a Struct in C: Why do I have to Specify the Name Twice?

In order to declare a struct in C, I have been using

typedef struct Foo Foo;

and then defining it at some point below.

Why do I have to specify the name of the struct (Foo) twice?

>Solution :

The format is

typedef old_type new_type

so for

typedef struct Foo Foo;

struct Foo is the old type and Foo is the new type, so whenever you type Foo it is really an alias for struct Foo.