rounding question

[keithmolo]

is it possible to round to the next highest multiple of four? for example:

if i have the values:

1.6, 2.3, 3.4, 3.9 - all of them need to be 4.

4.1, 5.6, 6.3 - all of them need to be 8.

8.1, 9.7, 10 - all of them need to be 12.

etc.

can the ceiling function do this? any suggestions?

keith

[PJYelton]

Depending on how many significant digits you need to worry about, off the top of my head I would do something similar to this (although I'm sure there is an easier way!):

x=int(x+3.999999)/4*4;

[zMan]

you could create a function that does it for you

int RoundBy4( float flValue )
{
     int iFoursInValue;
     int iValue;

     iValue = flValue + 4;

     iFoursInValue = iValue / 4;

     iValue = iFoursInValue * 4;

     return iValue;
}

something like this could work .... you probably have to do a little more work to it but it should work....

[Jubba]

I would do this...

#include <math.h>

double d = 2.4;
int i = (int)ceil(2.4);
while((++i)%4); // i is now round to highest multiple of 4

[keithmolo]

wow you guys are good. i just can't think like that

thanks a bunch.

keith

[PJYelton]

ZMan - yours unfortunately doesn't work for numbers that don't need to be rounded at all. For example, 4.0 should be 4, but yours will say 8. Thats why I added 3.99999 instead of 4.

Jubbas is probably best if you need to worry about an unlimited amount of numbers after the decimal point, but you'll have to change "while((++i)%4)" to "while((i++)%4)" otherwise something like 3.4 will come out as 8.

[Hunter2]

Instead of using 3.99999, use an if. If number % 4 == 0, return number.

[PJYelton]

But you can't use % with floats though.

[Hunter2]

if((int)number % 4 == 0)

Sheesh... figure it out yourself, you've done typecasting before. Do I really have to spoonfeed you?

[PJYelton]

LOL again doesn't work! Try that with 4.1!

[Hunter2]

Oh yeah? well:

if((((double)(int)number) == number) && ((int)number % 4 == 0))
     return number;
else
     return ((double)((int)(number + 4)/4*4));

HAH!

[golfinguy4]

wtf are you thinking? Ever heard of fmod?

[Hunter2]

Yes, but I never knew what it was...