c question?

[lipune]

what is the meaning of this struct ast_channel *(* const requester)(const char *type, int format, void *data, int *cause);
2-what is the use of
static struct hi
{
int a;
int k; char l;
};
3-what is the difference between char d[] and static char d[];
As i am new to this programing language so do not feel bad if this question is very easy one.
Regards
lipune

[kbw]

1. This is a variable declaration.
requester is a constant pointer (it cannot be changed and must be initialised on declaration) to a function that takes arguments const char*, int, void*, int* and returns struct ast_channel*.

2. There is no answer.

3. It all depends on where d is declared. The first form will give it the lifetime of its scope. The second has global lifetime.