Speed and Degree conversion string

[thesaint76]

Hi all,
i have a problem converting two strings taken from 2 columns of one datagridview.

One column is "speed" with valor "0.277778" but also "116.786023"
One column is "latitude" with valor "38.284572"

So I need to have speed with only 2 decimal after the point and I need to transform valor latitude from "38.284572" to "3828.4572"

For latitude I use this code:

Dim valor As String = CStr(DataGridView1.Rows(10).Cells("latitude").Value)
Dim sde As String = valor.Replace(".", "")
Dim lat As String = sde.Insert(4, ".")

I don't know if there is a simpler function

For speed I tryed with:

Format(CDec(DataGridView1.Rows(10).Cells("speed").Value), "0.00")

But I get "277778.00".. but I need "0.27"... or "116.78" for second valor .. How I can resolve?

[Delaney]

Why do you want to convert you values into string then modify them?
play directly with the values then convert to string if you need to show them.

What are the type of DataGridView1.Rows(10).Cells("latitude") and DataGridView1.Rows(10).Cells("speed") ?

Dim speed as "correct type"
Speed = math.round(DataGridView1.Rows(10).Cells("speed").Value, 2,MidpointRounding.ToEven)

Dim latitude as "correct type"
latitude =DataGridView1.Rows(10).Cells("latitude").Value * 100

or directly

Dim speed  = math.round(DataGridView1.Rows(10).Cells("speed").Value, 2,MidpointRounding.ToEven)

Dim latitude = DataGridView1.Rows(10).Cells("latitude").Value * 100

[thesaint76]

is not possible.. for latitude:

Dim latitude = DataGridView1.Rows(10).Cells("latitude").Value * 100

result is "3828457200" from an initial value of "38.284572"
I thought about it too, but since they are not decimal numbers, the points are in different positions, so I had to use the removal of the point from one position and moved to another position.


For speed I get error
cell of datagridview are type string.. and I get this error:

System.Reflection.AmbiguousMatchException: 'Risoluzione dell'overload non riuscita. Nessun elemento 'Round' pubblico può essere chiamato senza una conversione verso un tipo di dati più piccolo:
'Public Shared Function Round(value As Double, digits As Integer, mode As System.MidpointRounding) As Double':

if I modify in:

Dim speed = Math.Round(cdec(DataGridView1.Rows(10).Cells("speed").Value), 2, MidpointRounding.ToEven)

result is "277778"
from an initial value of "0.277778" but I need to get all number before point, and only 2 number after point

[Shaggy Hiker]

That doesn't make sense, to me. I'd want to do a bit more study of the problem. For example, if the value in the Latitude cell is really "38.284572", then there is no way that CDec(DataGridView1.Rows(10).Cells("latitude").Value) * 100 can be anything other than 3838.4572, and yet it looks like you are getting something else. Therefore, I think you ought to take a closer look at just this:

CDec(DataGridView1.Rows(10).Cells("latitude").Value)

what does that return?

[Delaney]

is not possible.. for latitude:

Dim latitude = DataGridView1.Rows(10).Cells("latitude").Value * 100

result is "3828457200" from an initial value of "38.284572"
I thought about it too, but since they are not decimal numbers, the points are in different positions, so I had to use the removal of the point from one position and moved to another position.

are you sure that DataGridView1.Rows(10).Cells("latitude").Value=38.28... or it is what it is show in the datagridview ?

just do a msgbox(DataGridView1.Rows(10).Cells("latitude").Value.tostring) to check

For speed I get error
cell of datagridview are type string.. and I get this error:



if I modify in:

Dim speed = Math.Round(cdec(DataGridView1.Rows(10).Cells("speed").Value), 2, MidpointRounding.ToEven)

result is "277778"
from an initial value of "0.277778" but I need to get all number before point, and only 2 number after point

try

dim converted_value as double
double.tryparse(DataGridView1.Rows(10).Cells("speed").Value, converted_value)
Dim speed = Math.Round(converted_value, 2, MidpointRounding.ToEven))

Comment: I thing the CDec may do strange conversion from a string. I rarely use decimal, i prefer double who are just enough for most of the case

edit : I just tested that

Label1.Text = Math.Round(CDec("0.277778"), 2, MidpointRounding.ToEven).ToString

and I got what I should expect : 0.28

so check also the real contents of DataGridView1.Rows(10).Cells("speed").Value

[OptionBase1]

I posit that the confounding mathematical results are happening because the decimal point is being interpreted as a thousands separator.

[Shaggy Hiker]

That would explain it, if that's how it works.

[thesaint76]

are you sure that DataGridView1.Rows(10).Cells("latitude").Value=38.28... or it is what it is show in the datagridview ?

just do a msgbox(DataGridView1.Rows(10).Cells("latitude").Value.tostring) to check

msgbox(DataGridView1.Rows(10).Cells("latitude").Value.tostring) I have "38.284572"


also I make:

Dim speed = Math.Round(CDec("0.277778"), 2, MidpointRounding.ToEven).ToString
MsgBox(speed)

result ever "277778" maybe regional issue?


My datagridview get valor from file csv (comma separated). I import it

dt.Columns.Add("speed", GetType(String))
....
fName = OpenFileDialog1.FileName
Dim TextLine As String = ""
Dim SplitLine() As String

If System.IO.File.Exists(fName) = True Then
     Dim objReader As New System.IO.StreamReader(fName, Encoding.ASCII)
     Dim index As Integer = 0

     Do While objReader.Peek() <> -1
           If index > 0 Then
                        TextLine = objReader.ReadLine()
                        SplitLine = Split(TextLine, ",")
                        dt.Rows.Add(SplitLine)
                Else
                        TextLine = objReader.ReadLine()
            End If
      index = index + 1
      Loop
      DataGridView1.DataSource = dt
   Else
      MsgBox("File Does Not Exist")
End If

[thesaint76]

wait... With this I get right result:

Dim speed = Math.Round(CDec(0.277778), 2, MidpointRounding.ToEven).ToString
MsgBox(speed)

result "0.28"

So without "" ? and how I can resolve

[techgnome]

since this is in .NET ... why not use Decimal.TryParse instead of CDEC?


-tg

[Shaggy Hiker]

CDec is better so long as you KNOW that the string can always be converted successfully. That seems likely, in this case. Of course, if any cells are empty, then CDec will fail on those.

This is a culture issue, from the looks of it. CDec on a string is going to use the cultural settings. CDec on a numeric literal is going to see a . as a decimal point in any culture, I believe.

You probably need to use Decimal.Parse with one of the overloads using culture information, but I've never done that:

https://learn.microsoft.com/en-us/do...arsing-numeric

[Delaney]

The regional issue would explain. check you regional setting to see if you have a . for thousand separation.

That's not something I didn't think about as it is the first thing I change on any new computer I have; I replace everywhere comma by dot for the decimal separator and remove any separator for thousand.

Edit: after checking , the thousand separator in Italia is a dot so it should be that

[Delaney]

You may change the culture for your application only. have a look here :

https://learn.microsoft.com/fr-fr/do...e?view=net-7.0

[PlausiblyDamp]

CDec is better so long as you KNOW that the string can always be converted successfully. That seems likely, in this case. Of course, if any cells are empty, then CDec will fail on those.

This is a culture issue, from the looks of it. CDec on a string is going to use the cultural settings. CDec on a numeric literal is going to see a . as a decimal point in any culture, I believe.

You probably need to use Decimal.Parse with one of the overloads using culture information, but I've never done that:

https://learn.microsoft.com/en-us/do...arsing-numeric

Personally I tend towards either Decimal.Parse / TryParse, partly because I can use the same in both VB and C# but I also find the syntax a bit more expressive. Under the hood CDec does a bit more work and is slightly slower too; admittedly the difference is measured in nanoseconds and not likely to make a difference unless performed inside of some very large loops....

[Shaggy Hiker]

I'm not going to go seek it out, but I was surprised at one point to find that MS advocated the use of CDec, CInt, etc. over the .Parse methods. I don't remember why.

[thesaint76]

okk RESOLVED

CultureInfo.CurrentCulture = New CultureInfo("en-US")
Dim speed As String = Math.Round(CDec(DataGridView1.Rows(10).Cells("speed").Value), 2, MidpointRounding.ToEven).ToString

msgbox(speed) and now we have 0.28

very Thankns to all