Two Consoles

[Benjamin]

The first problem for the Euler Project is as follows:

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5. 6. and 9. The sum of these multiples is 23. Find the sum of all the multiples of 3 or 5 below 1000.

So I wrote the code below, which gives 36,560. The Euler Project says this answer is incorrect. Can someone give me a hint about what's wrong? I honestly can't see it.

USES "Console"           
DIM i AS Integer         
DIM Total AS Word VALUE 0
                         
FOR i = 1 TO 999         
                         
IF MOD(i, 3) = 0 THEN    
Total += i               
ELSEIF MOD(i, 5) = 0 THEN
Total += i               
END IF                   
                         
NEXT                     
                         
CONSOLE_WRITELINE Total  
WAITKEY

[Benjamin]

I changed the question in the post. Please see above.

[Benjamin]

I simplified the logic, but still got 36,560, which the Euler Project says is incorrect.

USES "Console"                        
DIM i AS Integer                      
DIM Total AS Word VALUE 0             
                                      
FOR i = 1 TO 999                      
                                      
IF MOD(i, 3) = 0 OR MOD(i, 5) = 0 THEN
Total += i                            
END IF                                
                                      
NEXT                                  
                                      
CONSOLE_WRITELINE Total               
WAITKEY

What gives?

[dco045]

Hi Benjamin

The variable total is declared word

Word is 16 bits numbers from 0 to 65535

when i reaches 528 total is 65103 and for i = 530 total wraps to 97 instead of 65633

Use

dim total as dword

, 32 bits wide , up to 4294967295


Try this version:

Uses "Console"
DIM i AS Integer                     
DIM Total AS word VALUE 0             
DIM total_dw AS dword VALUE 0             
                                       
FOR i = 1 TO 999                   
                                       
IF MOD(i, 3) = 0 OR MOD(i, 5) = 0 THEN

Total += i                            
total_dw += i                            
printl i, total, total_dw
 END IF                               
         if  i = 530  then WaitKey           'pause                     
NEXT                                 
                                       
CONSOLE_WRITELINE Total      , total_dw            
PrintL "Press a key to end program"

'---Wait for a key press
WaitKey

Regards

DC

[Benjamin]

Hi DC,

Thanks so much for the detailed explanation. I learned a trick with those two variables. I'll have to remember that. Believe it or not, the first time I wrote it, I used Integer, but when I got a negative number, I knew I had wrapped around.

I'm relieved to know that I'm not losing my mind

Benjamin

[ErosOlmi]

To store numbers it is better to always use DWORD, LONG or QUAD for integer numbers and DOUBLE or EXT (EXTENDED) for floating point numbers.
Leave all other numeric data types for compatibility with data structure you need to use or external functions (DLLs) that specifically require them.

Even when you just need a simple counter for a loop, better to use LONG/DWORD.
They are much faster because native 32bit