OpenEuphoria

Re: [GEN] multiple pointers

• Posted by Derek Parnell <dparnell at BIGPOND.NET.AU> Oct 15, 2000
• 633 views

----- Original Message -----
From: "cense" <cense at MAIL.RU>
To: <EUPHORIA at LISTSERV.MUOHIO.EDU>
Sent: Sunday, October 15, 2000 4:41 PM
Subject: [GEN] multiple pointers



> how can euphoria handle multiple indirection? how can i get the value at
> the end of the pointer chain? in my case the the variable is a

> // in C
> char **list;

In C, "char **list" is read as "list is a pointer to a pointer which points
to a character". Often this situation is called a "handle". It is common in
Windows programming and extremely common in Macintosh and Amiga programming.
In C, a "char *" usually means a character string which is terminated by a
zero byte.

So, in the example above, if "list" is an atom containing a 32-bit machine
address then I'd do the following...

atom list
atom charptr
integer char
sequence string

    -- Get the pointer to the character data
    charptr = peek4u(list)

    -- Initialize the sequence
    string = ""

    -- Get the first character
    char = peek(charptr)

    -- Repeat until we find the terminating zero
    while char do

        -- Append the character just picked up
        string &= char

        -- Point to the next character
        charptr += 1

        -- Grab it from memory
        char = peek(charptr)

    end while

    -- See what we got.
    ? string

...but... if "list" is some other form of machine address, this method will
not work and you just might get a segmentation address.

------
Derek Parnell
Melbourne, Australia
(Vote [1] The Cheshire Cat for Internet Mascot)