>I'm trying to make a program that allows processes to send and receive
>from mailboxes, and I'm getting a little confused with something.  The
>signature for the receive function is:
> int receive(int mailbox, char ** a_message)
>So that a process can specify the mailbox it wants to read from and read
>the message in that mailbox into a_message.  The signature was given to us
>by our prof, but I don't understand why it's a double char pointer,
>instead just char * a_message enough?  My questions are, if someone wants
>to use this function, how would they call it, and how is a_message used
>within the function definition.

>Example:
>If this variable is declared for the message to be read into:
>char * buffer;
>is this how the function should be called?
>receive (1, &buffer);

>Also, within the function, how do you use the a_message variable.  So if
>you want to store message_from_mailbox in the variable a_message, would it
>be done like this:
>*a_message = message_from_mailbox;
>OR a_message = &message_from_mailbox;

>Any help would be greatly appreciated.  Once I know how this works, I can
>finish off the rest of my assignment easily (I hope)
>Thanks!
>Madeeha

> : I'm trying to make a program that allows processes to send and receive
> : from mailboxes, and I'm getting a little confused with something.  The
> : signature for the receive function is:
> :       int receive(int mailbox, char ** a_message)

> My best guess. It uses char** because the message you receive from mailbox
> is probably a set of strings. char** can represent a 2-dimensional array of
> strings. For example, one line of your message from mailbox is one string
> which is char*. and many lines are thus the whole message. Hope this helps.