DateTime Round Up and Down

Question

Ive been looking for a proper rounding mechanism but nothing I find seems to be exactly what I need.

I need to round up and round down seperately and I also need to acco

Answer 1

Another approach avoiding arithmetic using type long.

Using integer division, where a & b are positive integers:

a/b             // rounding down 
(a+b-1)/b       // rounding up 
((2*a)+b)/(2*b) // rounding to the nearest (0.5 up)

To round up:

public static DateTime UpToNearestXmin( DateTime dt, int block )
{
   int a = dt.Minute;
   int b = block;

   int mins = block * (( a + b - 1 ) / b );

   return new DateTime( dt.Year, dt.Month, dt.Day, dt.Hour, 0, 0 ).AddMinutes( mins );
}

To round down or to nearest, change the mins calculation as appropriate.

The minutes are rounded. The seconds & milliseconds are zeroed which is expected behaviour.