Thread: static array of function pointers.

I basically have some code that lets users register callbacks into a callback table at a specified index. There is one element in this table for each event that can trigger a callback. I basically do something like this:

In a header file

Code:

typedef struct _GMclient
{
    GMcommunicator gcomm;
    GMclient_callback callback_table[(int)MAX_CALLBACKS];
}GMclient;

typedef int (*GMclient_callback)(GMclient*, void*, void*);

Then I allow them to set the callback with a function that basically ends up doing this (in a .c file that includes the previous mentioned .h file):

Code:

void
GMclient_register_callback(GMclient *client,
			   GMclient_callback fxn,
			   int index)
{
    assert (client);
    assert (index < MAX_CALLBACKS);
    client->callback_table[index] = fxn;
    return;
}

Then later when I need to invoke that callback, I pull it out of the table

Code:

	    GMclient_callback *fxn = client->callback_table[CMD_INDEX];

However, I get compilation errors:

Code:

src/gmanager_client.c:43:6: error: a label can only be part of a statement and a declaration is not a statement

Any advice on what I'm doing wrong?

You don't seem to have a label in the code that you showed, so I do not know what is the problem. You do seem to have a typo error here though:

Code:

assert ((index < MAX_CALLBACKS);

That is, it should be:

Code:

assert (index < MAX_CALLBACKS);

I suggest that you post the smallest and simplest program that you expect should compile but which results in this compile error. For example, this program should demonstrate the error:

Code:

int main(void)
{
my_label:
    int n;
    return 0;
}

As you can see, my_label is a label for the declaration of n, but "a label can only be part of a statement and a declaration is not a statement".

Originally Posted by dayalsoap

I know I don't have a label so I'm confused why it's saying that error.

Then you really have to post a program that we can compile and see for ourselves. Otherwise, based on the error message and the code that you have shown, I am as stuck as you are.

Or at the very least post gmanager_client.c from lines 30+ to 50, indicating where exactly is line 43.