获得 Decimal 数的整数部分的最佳方法

返回小数的整数部分(在 c # 中)的最佳方法是什么？(这必须适用于可能不适合整型数的非常大的数字)。

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

这样做的目的是: 在 db 中插入一个十进制(30,4)字段，并希望确保不要试图插入一个对该字段来说太长的数字。确定小数的整数部分的长度是此操作的一部分。

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最佳答案

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!

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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.

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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.

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

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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

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   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
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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));
}

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