Best way to get whole number part of a Decimal num

Question

What is the best way to return the whole number part of a decimal (in c#)? (This has to work for very large numbers that may not fit into an int).

GetIntPart(343564564.4342) >> 343564564
GetIntPart(-323489.32) >> -323489
GetIntPart(324) >> 324

The purpose of this is: I am inserting into a decimal (30,4) field in the db, and want to ensure that I do not try to insert a number than is too long for the field. Determining the length of the whole number part of the decimal is part of this operation.

Answer 1

You just need to cast it, as such:

int intPart = (int)343564564.4342

If you still want to use it as a decimal in later calculations, then Math.Truncate (or possibly Math.Floor if you want a certain behaviour for negative numbers) is the function you want.

Answer 2

Very easy way to separate value and its fractional part value.

double  d = 3.5;
int i = (int)d;
string s = d.ToString();
s = s.Replace(i + ".", "");

s is fractional part = 5 and
i is value as integer = 3

Answer 3

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

Answer 4

   Public Function getWholeNumber(number As Decimal) As Integer
    Dim round = Math.Round(number, 0)
    If round > number Then
        Return round - 1
    Else
        Return round
    End If
End Function

Answer 5

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!

Answer 6

I hope help you.

/// <summary>
/// Get the integer part of any decimal number passed trough a string 
/// </summary>
/// <param name="decimalNumber">String passed</param>
/// <returns>teh integer part , 0 in case of error</returns>
private int GetIntPart(String decimalNumber)
{
    if(!Decimal.TryParse(decimalNumber, NumberStyles.Any , new CultureInfo("en-US"), out decimal dn))
    {
        MessageBox.Show("String " + decimalNumber + " is not in corret format", "GetIntPart", MessageBoxButtons.OK, MessageBoxIcon.Error);
        return default(int);
    } 

    return Convert.ToInt32(Decimal.Truncate(dn));
}