Format string problem

[Tular]

My teacher must be doing something I am not. I have followed her instructions and typed it all in as she said so, and I still cant get the boxes to function properly.

This code doesn't display the text, it only displays "(0,-23)(1,-10:C) (2,-8:C)":
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim fmtstr As String = "(0,-23)(1,-10:C) (2,-8:C)"
LSTRental.Items.Clear()
LSTRental.Items.Add("Equipment Half Full")
LSTRental.Items.Add(String.Format(fmtstr, "1. Rug Cleaner", 16, 24))
LSTRental.Items.Add(String.Format(fmtstr, "2. Lawn Mower", 12, 18))
LSTRental.Items.Add(String.Format(fmtstr, "3. Paint Sprayer", 20, 30))

This section of code keeps giving my the Value of String Type Can't be converted:

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim num As Integer
Dim amount = ", item="
Dim cost As Double
Dim fmtstr As String = "(0,-14)(1,-7:C)(2,-15:C)"
LSTBill.Items.Clear()
num = CInt(Item.Text)
amount = (TLTime.Text)
Select Case num
Case 1
Item = "Rug Cleaner"
cost = 16
Case 2
Item = "Lawn Mower"
cost = 12
Case 3
Item = ("Paint Sprayer")
cost = 20
Case Else
Item = ("")


Any help at all would be appreciated.

[Phil Weber]

Take a look at the format strings on this page: http://msdn.microsoft.com/en-us/library/txafckwd.aspx and see if you can tell how they're different from yours.

[JBourgeois]

The markers for the format should be delimited by French brackets {}, not parenthesis (). Your code should thus define the string as

Dim fmtstr As String = "{0,-23}{1,-10:C}{2,-8:C}"

(By the way, French brackets are not available on the standard French keyboards... why do you call them that way in English )

For the second section, you do not tell us on what line you get the error, which makes it hard to pinpoint the problem. But I see a lot of bad things in that code.

For the error specified, I suspect that it happens in

num = CInt(Item.Text)

If the content of the Text property (which is a String) is not a number, say "12A", it cannot be converted to an Integer and you get that error. You might use something as the following to prevent the problem:

If IsNumeric(Item.Text) Then
  num = CInt(Item.Text)
Else
  MessageBox.Show("Item does not contain a number")
End If

For an alternative, look for Integer.TryParse in Help.

And I suspect that in the project properties, Option Strict is turned Off and Option Strict is Off. Unfortunately, this is the default because Visual Studio is configured for dummies when you use it with Visual Basic. But this is a very bad way to work. Although it makes life easier for amateurs, it lets the system decide on what to do with unknown words and variable names, so you lose a lot of control.

If I am right, the following line might bring problems:

Dim amount = ", item="

No type is given there, and since Option Strict is Off, the compiler creates a variable called amount and gives it the value , item=.

I might be wrong, but I suspect that you were trying to create 2 variables, something as:

Dim amount="", item="" As String

Declaring 2 variables on the same line often lead to problems of that kind, you should use 1 line for each variable. Also, creating a variable without telling the compiler what its type is can also bring strange problems, even if Option Infer is

Because of the error in syntax, the variable Item is not declared, but is created on the fly then you use it in Item = "Rug Cleaner", which is usually not a good thing, for reasons I have no time to explain because I am hungry .

Option Strict should always be on, and Option Infer should always be off. You will have to be a little more careful about your declarations and assignments, but this would give you warnings about potential problems such as what I described.

Unless you thing that working 2 hours to correct a bug is better than taking 5 or 10 seconds to declare a variable properly.

[Phil Weber]

Jacques: In the U.S., we call them "curly braces." ;-)

[JBourgeois]

Phil.

Thanks for the info. I suppose that the French brackets I hear about all the time are only used by English canadians... who often have a strange relation with French canadians and tends to put the word French in strange places.

[Tular]

Thanx for all the help, so far I fixed the first problem. The second problem is not functioning a little different.

Updated Code:
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim num As Integer
Dim amount = ",item ="
Dim cost As Double
Dim Fmtstr As String = "{0,-14}{1,-7:C}{2,-15:C}"
LSTBill.Items.Clear()
num = CInt(mtxItemNum.Text)
amount = mtxTLTime.Text
Select Case num
Case 1
mtxItemNum.Text = "Rug Cleaner"
cost = 16
Case 2
mtxItemNum.Text = "Lawn Mower"
cost = 12
Case 3
mtxItemNum.Text = "Paint Sprayer"
cost = 20

End Select
Select Case amount
Case "H", "h"
amount = "(Half)"
Case "F", "f"
amount = "(Full)"
cost = cost * 1.5
End Select
If (mtxItemNum.Text <> "0") And (amount <> "") Then
LSTBill.Items.Clear()
LSTBill.Items.Add("***Receipt***")
LSTBill.Items.Add(String.Format(Fmtstr, mtxItemNum, cost, amount))
LSTBill.Items.Add(String.Format(Fmtstr, "Deposit", 30, ""))
LSTBill.Items.Add("")
LSTBill.Items.Add(String.Format(Fmtstr, "Total ", cost + 30, ""))
End If

End Sub



The problem now is when I click on the second button to display the meal I get this after the First line of the list(***Receipt***): System.Windows.MaskedTextBox. I asked the professor and she said to use a Masked text box, and i did. I also placed the items in the exactly how she showed, and it doesn't function as her's does. In the First button, if I select a number of the equipment, then time, than click the second button in the first masked text box for the equipment it changes it to text instead of the number.

[Tular]

not = now

[Tular]

if you want the seminar for the professor I can give you the weblink for it

[Tular]

Actually, nevermind I just fixed it myself. I forgot one stupid word in the second add line :P


Thanx for all the help guys. Ya'all helped me fix the first problem, and gave me clues for the second. I am really learning more from you guys than my professor :P