Real or float : whats the difference?

Helper

THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

On 26/02/2004 at 04:05, xxxxxxxx wrote:

User Information:
Cinema 4D Version:   8.2
Platform:
Language(s) :     C++ ;

---------
Hi
I'm trying to determine a percentage value by using the following code

    
    
    
    
     LONG a = 10;  
     LONG b = 50;  
     Real rperc = a/b*100;  
     LONG lperc = a/b*100;
    
    
    
    
     float fa = 10;  
     float fb = 50;  
     float fperc = fa/fb*100;
    
    
    
    
     GePrint("Real: " + RealToString(rperc));  
     GePrint("Long: " + LongToString(lperc));  
     GePrint("Float: " + RealToString(fperc));

Real always returns 0
Long always returns 0
float returns the correct answer of 20
So whats the difference between Real and float? Is it ok to use float instead of Real?
I don't know anything about a Mac, but Iv'e always assumed Real was there to use so everything is platform independant, because I thought a float wasn't?
This has confused me, because I realy need to return a percentage of a number and use it for StatusSetBar(), but how can I do this if LONG and Real datatypes don't return the correct results

Helper

THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

On 26/02/2004 at 06:04, xxxxxxxx wrote:

Hi Geespot,
I don't think that there's a diffrence between Real and float but there's a difference in your calculation:

try this and you will always get 20:

  
Real a = 10; //instead of LONG a = 10;  
Real b = 50; //instead of LONG b = 50;  
Real rperc = a/b*100;  
LONG lperc = a/b*100;  
  
float fa = 10;  
float fb = 50;  
float fperc = fa/fb*100;  
                       
GePrint("Real: " + RealToString(rperc));  
GePrint("Long: " + LongToString(lperc));  
GePrint("Float: " + RealToString(fperc));

Dividing a LONG value through another LONG value causes a rounding. In your example 10/50 == 0.

Helper

THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

On 26/02/2004 at 14:43, xxxxxxxx wrote:

Hi iwaitz,
The a and b variables were just examples, and my a and b variables I use in my plugin are in LONG and I can't change that because they are returned by certain functions within the SDK.
But I found out why, it was because the LONG a,b variables were rounding the result to 0, just like you said. A simply cast did the trick

    
    
    
    
    Real rperc = (Real)a/(Real)b*100;

I also found in the ge_win_math.h header this:

    
    
    
    
    typedef float        Real;

so Real's and float are exactly the same. I suppose MAXON used Real to keep it friendly with the C4D interface.
I must say, it was the first time I looked at that header file, it's an interesting file because it explains the datatypes, ie

    
    
    
    
    #define pi  3.1415926535897932384626433832795

I guess MAXON wanted to have PI really precise :)

Helper

THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

On 26/02/2004 at 15:18, xxxxxxxx wrote:

That´s not really precise as PI has endless numbers after the decimal place ;)