Best way to get whole number part of a Decimal number

I think System.Math.Truncate is what you're looking for.

By the way guys, (int)Decimal.MaxValue will overflow. You can't get the "int" part of a decimal because the decimal is too friggen big to put in the int box. Just checked... its even too big for a long (Int64).

If you want the bit of a Decimal value to the LEFT of the dot, you need to do this:

Math.Truncate(number)

and return the value as... A DECIMAL or a DOUBLE.

edit: Truncate is definitely the correct function!

Depends on what you're doing.

For instance:

//bankers' rounding - midpoint goes to nearest even
GetIntPart(2.5) >> 2
GetIntPart(5.5) >> 6
GetIntPart(-6.5) >> -6

or

//arithmetic rounding - midpoint goes away from zero
GetIntPart(2.5) >> 3
GetIntPart(5.5) >> 6
GetIntPart(-6.5) >> -7

The default is always the former, which can be a surprise but makes very good sense.

Your explicit cast will do:

int intPart = (int)343564564.5
// intPart will be 343564564

int intPart = (int)343564565.5
// intPart will be 343564566

From the way you've worded the question it sounds like this isn't what you want - you want to floor it every time.

I would do:

Math.Floor(Math.Abs(number));

Also check the size of your decimal - they can be quite big, so you may need to use a long.