OpenEuphoria

Re: C Programers

• Posted by Jason Gade <jaygade at ??hoo.com> Jul 23, 2007
• 525 views

don cole wrote:
> 
> Hello C Programers,
> 
>    Can any of you translate this to Euphoria?
> 
> int sum_list(struct list_node *l)
> {
>    if(l == NULL)
>       return 0;
>     return l.data + sum_list(l.next);
> }
> 
> Don Cole

I've read the replies to this, but I wanted to go back to the original. This
example in C doesn't translate very well into Euphoria code, just so you know.

First, let's examine the C version:
int sum_list(struct list_node *l)
-- this defines the function, returning an integer, and takes as a paramater a
pointer to a list_node structure.

A list_node structure is probably defined like this:
struct list_node {
        int *data; -- or float, or double, or whichever
        list_node *next;
        };

See, it's kinda recursive on it's own. 

if (l == NULL){...}
-- Generally, a pointer will either contain a valid RAM address (which has
already been allocated) or NULL which is usually a fancy way of saying zero. NULL
is almost always a marker for an invalid pointer.

A linked list is one way the C uses to simulate sequence-like data that is
usually iterated through in order from first to last.

Another reason to use linked lists in C is that C does not have dynamic arrays
-- once you declare an array its size is basically fixed.

Heh. That probably sounds pretty complicated.

While I could see a linked-list-type structure useful sometimes in Euphoria, it
really wouldn't be needed here because sequences are dynamic. You don't have to
manually allocate or deallocate memory in order to use them.

--
"Any programming problem can be solved by adding a level of indirection."
--anonymous
"Any performance problem can be solved by removing a level of indirection."
--M. Haertel
"Premature optimization is the root of all evil in programming."
--C.A.R. Hoare
j.