Hello,
I'm new to the forums, so if I have placed this message in the wrong subject, I apologize. But, I'm hoping someone might be able to help me.
I am trying to compare two numbers in VB.net. I want to compare all the digits to the left of the decimal point and only the first digit to the right to see if they match.
For example: 8.64 and and 8.69 would be a match because all that I'm concerned with is the first digit to the right of the decimal point.
But, if I use the Math.Round, it would round 8.64 to 8.6 and 8.69 to 8.7 - and then they wouldn't match.
I thought I could determine the length of the number and then trim the digits, but there could any number of digits to the left and/or right of the decimal point. So, I don't know how I would accomplish that.
Can anyone help Does anyone have any suggestions
Thanks,
Chris Heritage
Rounding Help
PareshGheewala
After looking at system.math.floor and system.math.ceiling - to get what we might consider normal rounding where if the last digit is a 5 or greater we round up and a 4 or less we round down then you may use something like the following.
This may be what your looking for.
Module Module1
Sub Main()
Dim a As Single
Dim b As Single
a = System.Math.Round(8.64, 1)
b = System.Math.Round(8.69, 1)
Console.WriteLine(a.ToString)
Console.WriteLine(b.ToString)
a = (System.Math.Truncate(8.64 * 10) / 10)
b = (System.Math.Truncate(8.69 * 10) / 10)
Console.WriteLine(a.ToString)
Console.WriteLine(b.ToString)
'DIFFERENT
a = NormalRound(8.64)
b = NormalRound(8.69)
Console.WriteLine(a.ToString)
Console.WriteLine(b.ToString)
'DIFFERENT
a = NormalRound(8.64, 1)
b = NormalRound(8.69, 1)
Console.WriteLine(a.ToString)
Console.WriteLine(b.ToString)
'SAME
a = NormalRound(8.642, 2)
b = NormalRound(8.644, 2)
Console.WriteLine(a.ToString)
Console.WriteLine(b.ToString)
End Sub
Function NormalRound(ByVal d As Double, Optional ByVal DecimalPlaces As Integer = 1) As Double
Dim i As Integer = (10 ^ DecimalPlaces)
Dim x As Integer
x = d * i
If x Mod i >= 5 Then
Return System.Math.Floor(x) / i
Else
Return System.Math.Ceiling(x) / i
End If
End Function
End Module
Moon with Ice
aclysma
I also ran into this problem a while back and while my solution might not be the optimal it works.
I found the trick is to compare the values as String types. Here's and example:
Dim a, b As Decimal
a = 8.64
b = 8.69
'this does not work
If a.ToString("N1") = b.ToString("N1") ThenMsgBox(
"The truncated numeric values match") End If'you have to compare them as strings
Dim c, d As Stringc = a.ToString
d = b.ToString
If c.Substring(1, c.IndexOf(".") + 1) = d.Substring(1, d.IndexOf(".") + 1) ThenMsgBox(
"The truncated string values match") End IfCodemasterMM
Use Math.Floor instead of math.round, after you multiply your numbers by 10.
Scythen
If your not rounding then your truncating.
I'd shown a number of variations on a theme, truncating, rounding in a manner we are more accustomed to rather than the bankers rounding that is used by default which is often somewhat confusing to people at first what is occuring.
All were shown in the examples.
Pick which one is most applicable.
ZardoS42
Um, why doesn't a simple Math.Floor work since you don't want any rounding according to the origional post. Specifially, spotty, your function doesn't answer the origional question, which is to prevent rounding.
RajatS
Sure what your seeing is the effect known as bankers rounding. You could truncate the values and do something similar to the following
Module Module1
Sub Main()
Dim a As Single
Dim b As Single
a = System.Math.Round(8.64, 1)
b = System.Math.Round(8.69, 1)
Console.WriteLine(a.ToString)
Console.WriteLine(b.ToString)
a = (System.Math.Truncate(8.64 * 10) / 10)
b = (System.Math.Truncate(8.69 * 10) / 10)
Console.WriteLine(a.ToString)
Console.WriteLine(b.ToString)
End Sub
End Module
This would truncate to one decimal place. Obviously you could wrap this up in some function. I'm sure the framework must have something to handle this and will continue to search.
Ramesh_Kumar_02a072