Re: Ada Recursion with strings

["Jeffrey R. Carter" <spam.jrcarter.not@spam.acm.org>]

Joe wrote:
> 
>    function IP_String (Word : Word_Type;
>                        IP_String : String := "") return String
> is

>          return IP_String( Word / 2**8,
>                            "." & Sub_String & IP_String);

> There are 2 errors with this that I don't understand.  First, Ada
> expects an integer for (word / 2**8).  Is this because word_type is
> outside the standard integer range?  How do I get a division operator
> that works on word_type?

This is a misleading error msg.

Your problem is that your function IP_String has a parameter of the same name. 
Within the function, IP_String refers to the parameter. Thus,

return IP_String (...);

is interpreted as indexing into the String. Since "Word / 2 ** 8" is of type 
Word_Type and String is indexed by Integer, you get the error msg about 
expecting Integer.

Though you can refer to the function IP_String within itself as 
Ip_Packet.IP_String, it would be better to change the name of the parameter to 
something other than the name of the function, like Current_Result.

How many times does the magic number 2 ** 8 appear in this short example?

-- 
Jeff Carter
"I unclog my nose towards you."
Monty Python & the Holy Grail
11