Decimal Formatting Help

[Dragnorian]

Hello fellow forumers! I have been having this issue, I have made this program that basically counts how many say tenths are in a given range like say 10 to 0. Well, in the Display when the data is being shown, I get an output of: 10, 9.9,9.8,9.7,9.6,9.5,9.4,9.3,9.2,9.1,9, etc...
Well, I am wanting to make this program look professional so say where the 10 is, I would like it to say 10.0 or if they are say doing thousandths, it be like 10.000, Know what I mean? I have been to stackexchange, MSDN, but none pose a good solution to this matter. Any help works! Thanks

Code Area:

'Where I want to format
        While (startNum >= EndNum + 0.1)
            counter += 1
            startNum -= 0.1
            Data += startNum & vbNewLine
            valprint += startNum & Space(4)
            pgbProgress.Increment(1)
        End While
        starting = txtStart.Text
        rtbDisplay.Text = starting & vbNewLine & Data & vbNewLine
        rtbVerticalText.Text = starting & Space(4) & valprint
        lblCount.Text = counter
        btnClear.Enabled = True
        btnCount.Enabled = False
        txtStart.Enabled = False
        txtEnd.Enabled = False
    End Sub

[techgnome]

Well, w/o seeing the code you have, it's hard to say what you should be doing differently.

-tg

[jmcilhinney]

When you call ToString on a numeric value, you can provide a format specifier to control what the output looks like. If you want one decimal place in the output then you can use "n1" or "f1" as the specifier. Change the number in the specifier to change the number of decimal places. You should read about numeric format strings in the MSDN documentation to learn more about what options there are.

[Dragnorian]

Added code, sorry about that

[Dragnorian]

I read up on that before I came onto this post I made but where I thought I would put it which is where I declare what rtbDisplay.Text equals, just crashes the program. That is the main issue of finding where to put it lol. Putting it in the while statement also crashes program too.

[jmcilhinney]

You can only use a numeric format string when converting an actual number to a String. If you already have a String then you can't format it as a number. The place that you convert a number to a String is here:

Data += startNum & vbNewLine

so that's where you should do the formatting:

Data &= startNum.ToString("n2") & vbNewLine

Notice that I also changed '+=' to '&=". While you can use '+' to concatenate Strings in VB.NET, you should never do so. You should ALWAYS use '&'. That's because '+' is actually the addition operator and, while addition of two Strings is implemented as concatenation, addition of one String and something else is generally not, so '+' may not behave as expected in some circumstances. '&' is the concatenation operator and will ALWAYS behave as expected.

[Dragnorian]

Here are my declarations:

    Dim startNum, starting, custom, progress As Decimal
    Dim total As Long
    Dim EndNum, increment As Decimal
    Dim Data, numdata As String
    Dim counter As Integer = 0
    Dim time As Integer = 1
    Dim TimeCount As Integer = 0
    Dim valprint As String

I should make Data and Startnum and Endnum into string variables instead of Decimal variables? Therefore getting the results I want?

[Dragnorian]

I tried that(hopefully the correct way) and it didn't work. I tried changing it to different ways but those didn't work either. I changed the startnum declaration to a string instead of a decimal like I thought would be the way to do it.

[jmcilhinney]

Post the code that you think is right and tell us what actually happens when you run it. "It doesn't work" is rarely very helpful. We need to know what doesn't work and how it doesn't work in order to know what needs to be done to fix it.

[Dragnorian]

    Dim startNum, starting, custom, progress As String 'Changed to String
    Dim total As Long
    Dim EndNum, increment As Decimal
    Dim Data, numdata As String
    Dim counter As Integer = 0
    Dim time As Integer = 1
    Dim TimeCount As Integer = 0
    Dim valprint As String

I changed the variable from a decimal to a string.

            Data &= (startNum.ToString("n2") & vbNewLine) 'Can't Go Here

I then convert the string to a string? That doesn't look right but I am still learning.

After I run the program, the program crashes with an exception unhandled error.

[jmcilhinney]

What did I say in post #6?

You can only use a numeric format string when converting an actual number to a String. If you already have a String then you can't format it as a number.

Now let's look at your code:

    Dim startNum, starting, custom, progress As String 'Changed to String
    Dim total As Long
    Dim EndNum, increment As Decimal
    Dim Data, numdata As String
    Dim counter As Integer = 0
    Dim time As Integer = 1
    Dim TimeCount As Integer = 0
    Dim valprint As String

I changed the variable from a decimal to a string.

            Data &= (startNum.ToString("n2") & vbNewLine) 'Can't Go Here

I then convert the string to a string? That doesn't look right but I am still learning.

After I run the program, the program crashes with an exception unhandled error.

Do you not see the issue there? People are commonly quite lax with data types when they start out and this is a perfect example of why they need to tighten up ASAP. If, as the name suggests, 'startNum' is supposed to represent a number then it should be declared as the appropriate numeric type. String is ONLY for text. If you want to treat something as a number then it needs to be a number, NOT text. You only convert numbers, dates, etc to text for the purposes of display or serialisation, e.g. saving to a text file. In your code, numbers should ALWAYS be stored in numeric variables.

[Dragnorian]

Yes I know that I Need to tighten up on it. I figured that was a bit strange, I would be lying if I said I never misread anything. I got it all now, thank you for teaching me this and sorry for the accident I made. This will surely help my program. I had been trying different formats(attempted) before coming here. Thank you!

[jmcilhinney]

Yes I know that I Need to tighten up on it.

Pretty much everyone does to begin with. I think that it's often because data goes into and out of a console application as text and VB in particular can be quite forgiving in many cases, performing implicit conversions much of the time. Proper use of data types is critical to create software of any significance though.

[Dragnorian]

Yeah, I will be working on that. Thank you again for the help!

[Dragnorian]

.,/'

[Dragnorian]

That whole formatting issue was because the user can predetermine a set increment value that I have defined in the code but what about a custom increment value that the user defines, not me? I thought doing something like .ToString("n#") would work but no. I need something to figure out how it can calculate if the custom value is either an integer or a decimal number then figure out if decimal, how many places it should go to then do the same basic format as the .ToString("n1") does. Is this possible in Visual Basic?.

[jmcilhinney]

E.g.

Private Function GetFormatSpecifier(increment As Double) As String
    Dim formatSpecifier As String
    Dim text = increment.ToString()
 
    If text.Contains(".") Then
        Dim fraction = text.Substring(text.IndexOf(".") + 1)
 
        formatSpecifier = "n" & fraction.Length
    Else
        formatSpecifier = "n0"
    End If
 
    Return formatSpecifier
End Function

That's untested but I believe it should do the job. You can test and adjust if required.

[Dragnorian]

Okay, I will test it

[Dragnorian]

I've never worked with functions before, so where would I put it? Inside the button?

[wes4dbt]

If your using a form then just add it to your form. If your going to be calling it from multiple forms then declare the function "Public" and add it to a Module.