World: r3wp

use Cheyenne

which is also free :)

Hi,so i am quite new to the rebol community and have been assigned 
a project to work on.So to be frank i started reading rebol 2 days 
ago and i am quite confused since i worked with c++ before that.I 
am stuck at flow control and operators(sad i know).So basicaly i 
thought of when i moved from delphi to c++,basically if one of you 
guys can provide me with a rebol version of this small program i 
whipped up(flow control number check-the basics) it would be of great 
help to me,so here is my program and thanks in advance.
    

It inputs an integer number n and outputs the sum: 1+22+32+...+n2.I 
use input validation for n to be positive.
#include <iostream>
using namespace std;
    
int main()
{
     int n;
     cin >> n;
     if (n < 0) return 1;
     int sum = 0;
     int i = 0;
     while (i <= n) sum += i*i;
     cout << sum;
     return 0;
}

welcome to REBOL Martin , C++ to REBOL is probably the biggest jump 
you can make, but I'm sure you'll see the light in the end  ;-)


If your feel like REBOL is breaking the rules (those which you are 
used to in other languages), in fact see it more like, there are 
much *less* rules in REBOL.


although this freedom is dauting at first, I hope you'll come to 
appreciate it.

I'll give you a convertion in a few secs...

welcome to REBOL :-)

wow thanks alot maxim that would really help me get my act together 
it`s just that basic flow control and inputs are my weacknesses in 
this langueage

oh and oops the code does: 1+2^2+3^2+...+n^2

yeah my bad :D

thanks for the worm welcome

yea.. hehe I was wondering  ;-)

well copying from linux does that to you

in the above you use   cin   ...   do you expect the input to be 
piped ?

piped?

basically c input

it inputs a vallue for a varriable

ok.

this >> is input and << is output

yeah.. I don't use the C++ console ops a lot, I do C mainly.

but here goes...

n: to-integer ask "enter a number"
if  n < 0  [quit/return 1]
sum: 0
i: 0
while [ i <= n ] [ sum: sum + probe (i * i)  i: i + 1]
print sum

basically when you have cin>>n it awaits a vallue to be inputted 
in the console window

rebol returns 0 by default when you are the end of a script... so 
no need to add it at the end.

aha

ok so i just dont understand 2 lines of the code

sum:0

i:0

note, I added a little probe which prints the value at each step.


I did this to show you one powerfull aspect of REBOL... you can insert 
functions like *chains*

wow

the probe actually is transparent and returns the value it received 
while printing it.

alemar, in rebol, the assignment is done via :, not =

aaa like delphi

i get it

hmm, delphi uses :=, IIRC? But I might be confused by CA Visual OBjects 
I used in the past :-)

just a few functions don't return values (like print) in this case 
you will get an error, but the error should give you clues

well in delphi you define a value by := and : only explaines the 
type (boolean,integer..

aha gr8

that's one powerful aspect of REBOL: it figures out the type on its 
own, mostly.

trying to compile the code now but the compiler from the site is 
a bit tricky

** Script error: n has no value
** Where: while
** Near: while [i <= n] [sum: sum + probe (i * i) i: i + 1]

:D

ok is the Near error a syntax error in the cycle?

the main difference in REBOL is that everything you can manipulate 
is a value, even functions and objects don't have a special syntax 
to use... they are values just like anything else.

there is no compiler...

hehehe... if you paste it directly in the console, the ask will intepret 
the next line as the answer  ;-)

then what am i using :D

:-)

so it triggers an error and n is never assigned any value  ;-)

yeah exctly i understood that

alemar - rebol is an interpreter ...

for the console, just replace the first line by 

n: 5