How would I get the number after a decimal point in VB.NET

Question

Can anyone give me an easy way to find out the numbers after the decimal point of the double?
All i need to do is to find out if the number ends in 0 like 1.0 or 10.0 or 32

Answer 1

If your input is a string, and you want to identify strings that have decimals, but where those decimal places are all zero, then you could use a regular expression:

var regex = new Regex("^-?\\d+\\.0+$");
if (new Regex.IsMatch(input))
{
    // it's in the format you want
}

Answer 2

It's been a while, nevertheless my solution:

I also used the mod function, but you have to be careful with that as there are precision "problems" with the data type 'Double':

Dim numberDbl As Double = 1.2
Dim modValDbl As Double = 1.0
Dim remValDbl As Double = numberDbl Mod modValDbl
'remValDbl = 0.19999999999999996 -> not 100% precise

Dim numberDec As Decimal = 1.2D
Dim modValDec As Decimal = 1D
Dim remValDec As Decimal = numberDec Mod modValDec
'remValDec = 0.2 -> correct

Therefore I wrote this function: (example: number = 1.25)

• I first take the parameter number and mod it with its own integer (1.25 mod 1)
• so I get the decimal value of my number and store it to remVal = 0.25
• in the loop I keep multiplying remVal with 10 and compare this value with the same truncated value (i.e.: 2.5 <> 2) until they are the same
• with every loop I increment the multiplier by 10

• as soon the two values match (i.e.: 25 = 25) I can return my decimal value using remVal and multiplier

  Public Shared Function getDecimalPlaces(number As Double) As Double
  Dim modVal As Integer = CInt(If(Math.Truncate(number) = 0, 1, Math.Truncate(number)))
  Dim remVal As Decimal = CDec(number) Mod modVal
  Dim retVal As Double = 0
  
  Debug.WriteLine("modVal: " + modVal.ToString)
  Debug.WriteLine("remVal: " + remVal.ToString)
  Dim multiplier As Decimal = 1
  
  While remVal * multiplier <> Math.Truncate(remVal * multiplier)
      Debug.WriteLine("remVal * multiplier <> Math.Truncate(remVal * multiplier): " + (remVal * multiplier).ToString + " <> " + (Math.Truncate(remVal * multiplier)).ToString)
      multiplier *= 10
      Debug.WriteLine("remVal * multiplier <> Math.Truncate(remVal * multiplier): " + (remVal * multiplier).ToString + " <> " + (Math.Truncate(remVal * multiplier)).ToString)
  End While
  
  retVal = CDbl(remVal * multiplier)
  
  Debug.WriteLine("remVal: " + remVal.ToString)
  Debug.WriteLine("multiplier: " + multiplier.ToString)
  Debug.WriteLine("retVal: " + retVal.ToString)
  Return retVal
  End Function
  
  'Output with number = 1.25
  'modVal: 1
  'remVal: 0,25
  'remVal * multiplier <> Math.Truncate(remVal * multiplier): 0,25 <> 0 -> true
  'remVal * multiplier <> Math.Truncate(remVal * multiplier): 2,50 <> 2 -> true
  'remVal * multiplier <> Math.Truncate(remVal * multiplier): 2,50 <> 2 -> true
  'remVal * multiplier <> Math.Truncate(remVal * multiplier): 25,00 <> 25 -> false: exit while
  'remVal: 0,25
  'multiplier: 100
  'retVal: 25