Trick to use Rounded Floats

[BackupUser]

Code updated For 5.20+

Restored from previous forum. Originally posted by MrVainSCL.

Hi @ all
I searches a way to use rounded floats (add, div and more) in an app... so i have had following idea...

In order to round a value, you can use the Int() command. This command rounds the number to an integer like following example:

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    tmp1 = Int(102.314)    ; Result will be = 103 
    tmp2 = Int(107.241)    ; Result will be = 107 

If you want maintain however two right-of-comma positions, you can use a small trick - you have to shift the comma before

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    tmp1 = 102.314 * 100   ; Result will be = 10231.4 
    tmp2 = 107.241 * 100   ; Result will be = 10724.1 

Then you have to round this val with Int() command:

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    tmp1 = Int(10231.4)    ; Result will be = 10231 
    tmp2 = Int(10724.1)    ; Result will be = 10724 

Now we have all muliplied by the factor 100 to get large numbers - thus we divide it again by 100

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    tmp1 = 10231 / 100     ; Result will be = 102.31 
    tmp2 = 10724 / 100     ; Result will be = 107.24 

Now i will follow up with an small example:

[BackupUser]

Restored from previous forum. Originally posted by MrVainSCL.

Code: Select all

Upsss.. example has wrong formated... so its on the database but you cant see it... started with

;( --- So here it is...

Now i will follow up with an small example:

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    #ListPrice = 103.115 
    #Commas    = 2 
    Factor     = Pow(10,#Commas)  
    ;
    NewPrice.f = Int (#ListPrice * Factor) / Factor 
    ;
    OpenConsole()
    PrintN ("ListPrice "+StrF(#ListPrice,3)+" is rounded: "+StrF(NewPrice,3)+ " = "+StrF(NewPrice,2))
    Sleep_(3000)
    End 

Hope this will help some guys for easy operations...!? Article by me!


PIII450, 256MB Ram, 80GB HD + 6,4 GB, RivaTNT, DirectX8.1, SB AWE64, Win2000 + all Updates...

greetz
MrVainSCL! aka Thorsten

[BackupUser]

Restored from previous forum. Originally posted by MrVainSCL.

Here is an correct working example...

Code: Select all

    #ListPrice = 103.1595 
    #Commas    = 2 
    Factor     = Pow(10,#Commas)  
    ;
    NewPrice    = Int (#ListPrice * Factor) 
    NewPrice2.f = NewPrice / Factor 
    ;
    OpenConsole()
    PrintN ("ListPrice "+StrF(#ListPrice,3)+" is rounded: "+StrF(NewPrice2,4)+ " = "+StrF(NewPrice2,2))
    Delay(3000)
    End

PIII450, 256MB Ram, 80GB HD + 6,4 GB, RivaTNT, DirectX8.1, SB AWE64, Win2000 + all Updates...

greetz
MrVainSCL! aka Thorsten

[BackupUser]

Restored from previous forum. Originally posted by tinman.

Your floating point values will still get rounding errors when you divide by 100 if the number cannot be stored exactly in the float.

If you really need to do this, and you *always* want to maintain the 2 digits after the decimal place you are better off using a longword to store the values (multiplied by 100 of course) and therefore keeping the exact accuracy in all your calculations.

You then only need to worry about displaying the result, where you could use a float, or better still do it manually.


--
It's not minimalist - I'm increasing efficiency by reducing input effort.
(Win98first ed. + SP1, PB3.40)

[BackupUser]

Restored from previous forum. Originally posted by Danilo.

> tmp1 = Int(102.314) ; Result will be = 103

Result is 102, because 3 gets rounded down.

cya,
...Danilo

(registered PureBasic user)

[BackupUser]

Restored from previous forum. Originally posted by MrVainSCL.

upss... yes sure... you are right danilo...
small mistake

PIII450, 256MB Ram, 80GB HD + 6,4 GB, RivaTNT, DirectX8.1, SB AWE64, Win2000 + all Updates...

greetz
MrVainSCL! aka Thorsten