Visual Basic

7-Jul-09 5:27

Hi. Im new to visual basic 2008. I am now learning classes and how to make an instance of a class. Below are my codes. I have a problem in which the system says my "Calculator.DateCalc2008()" is not defined.

The following is my class code.

PublicClass DateCalc2008

Private _startDate As DateTime
Private _endDate As DateTime
Private _span AsInteger

PublicProperty StartDate() As DateTime
Get
StartDate = _startDate
EndGet
Set(ByVal value As DateTime)
_startDate = value
EndSet
EndProperty

PublicProperty EndDate() As DateTime
Get
EndDate = _endDate
EndGet
Set(ByVal value As DateTime)
_endDate = value
EndSet
EndProperty

PublicProperty Span() AsInteger
Get
Span = _span
EndGet
Set(ByVal value AsInteger)
_span = value
EndSet
EndProperty

PublicSub IncreaseDate()
EndDate = StartDate.AddDays(Span)
EndSub
EndClass

This is my object codes. Reference from above.

PublicClass Calculator

PrivateSub StartDatePicker_ValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles StartDatePicker.ValueChanged

Dim myCalc AsNew Calculator.DateCalc2008() //THE PROBLEM!

myCalc.StartDate = StartDatePicker.Value
myCalc.Span = 7
myCalc.IncreaseDate()
EndDate.Text = myCalc.EndDate.ToString()
EndSub
EndClass

DoctorMick7-Jul-09 5:36

DoctorMick

7-Jul-09 5:36

I suspect VB is not happy because it is confusing the class Calculator with the namespace you are using. If both the calculator class and the DateCalc2008 class are in the same namespace you should be able to omit Calculator when declaring your variable, i.e.

Dim myCalc AsNew DateCalc2008()

nlarson117-Jul-09 5:37

nlarson11

7-Jul-09 5:37

Dim myCalc As New Calculator.DateCalc2008() //THE PROBLEM!

take off the work Calculator

Dim myCalc As New DateCalc2008()

DateCalc2008 would need to be nested within Calculator to be declared like that.

'Never argue with an idiot; they'll drag you down to their level and beat you with experience.' ~ anonymous

'Life's real failure is when you do not realize how close you were to success when you gave up.' ~ anonymous

gjx_junxian19897-Jul-09 5:42

7-Jul-09 5:42

I tried, but still has the error. ok. cause i following the directions of a book, it taught me this way. "To run your new DLL file, you need to add a project with a user interface to the same solution that holds your DLL project."

so, the Class DateCalc2008 is the .dll file which is used as a reference for the user interface which is the class Calculator.

Thanks Alot! =)

Christian Graus7-Jul-09 5:44

7-Jul-09 5:44

Does your new project have a reference to your dll ? If not, that would cause this error.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

gjx_junxian19897-Jul-09 5:49

7-Jul-09 5:49

yup. it does. Assuming i am following the book correctly, which im pretty sure i am.

what does each part of this code means anyway? "Dim myCalc As New DateCalc2008()".

just a thought, so usually if i were to have a class and want to create instances of it, i could just write it all out on the long sheet of codes instead of using the .dll as reference method?

Thanks a million!

Christian Graus7-Jul-09 5:55

7-Jul-09 5:55

gjx_junxian1989 wrote:
Dim myCalc As New DateCalc2008()

It means, create a new object, call it myCalc, and initialise it by calling the constructor of DateCalc2008.

gjx_junxian1989 wrote:
ust a thought, so usually if i were to have a class and want to create instances of it, i could just write it all out on the long sheet of codes instead of using the .dll as reference method?

The only reason for the dll reference, is that you put the code in a dll. You would rarely do this, and I'm shocked that a book is telling you to mess with dlls, before explaining to you what a constructor does. If you have a reference to the dll, then you DO need to reference the full namespace of the dll, to get access to the object. If you start to type in the name of the top level namespace in the dll, autocomplete should kick in. If it doesn't, I doubt you have that reference. Also, if you made the reference, THEN added the class, you probably need to remove and re-add the reference to update it.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

gjx_junxian19897-Jul-09 6:03

7-Jul-09 6:03

ic. Thanks alot. so if im not wrong, Dim myCalc As New DateCalc2008(), creates an object myCalc, which thus enables me to gain access to functions and variables in the class DateCalc2008 and assigning values to it. so the DateCalc2008 is like a template for many other uses of same application? But usually we write classes and make objects of the class in a single sheet of code?

Christian Graus7-Jul-09 6:27

7-Jul-09 6:27

gjx_junxian1989 wrote:
so the DateCalc2008 is like a template for many other uses of same application? But usually we write classes and make objects of the class in a single sheet of code?

Not really. A class would be created in one file inside your project, other classes, in other files, would create instances of the class and use them

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

gjx_junxian19897-Jul-09 6:31

7-Jul-09 6:31

ok. Hey, thanks, you've been a great help. Is there anyway i can contact u in future if i have problems with VB? Big Grin | :-D

Christian Graus7-Jul-09 6:34

7-Jul-09 6:34

I don't actually do VB, I just help here b/c it's all .NET. There's other people on these forums far better at VB than me, your best bet is to ask here, I'm here all the time, so I'll answer if no-one else does

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

gjx_junxian19897-Jul-09 6:36

7-Jul-09 6:36

Alright! Thanks man! Big Grin | :-D

Convert String DataType To Form Object

chilinhhacker13-Jul-09 18:31

chilinhhacker

13-Jul-09 18:31

I'm not good at English.

Not enough data to answer, because you didn't say about all the parts in your project and your project name.

May be you have a class named "DateCalc2008" and a form named "Calculator". The form "Calculator" has a control named "StartDatePicker", and you created a subroutine which handles "StartDatePicker.ValueChanged" event.

The error is: The form "Calculator" doesn't have a member named DateCalc2008.
You should fix your code like this:

Dim myCalc As New {project name}.DateCalc2008

I hope this will be an useful answer.

Good luck !

chilinhhacker

faravani7-Jul-09 3:12

faravani

7-Jul-09 3:12

I have a combobox that all my formname such as form1,form2,... listed that.
i want when i select a formname from combobox the component of selected form list in listbox such as button1,textbox1,....
but when i choose a formname from combobox because it is a string havenot form property such as control,enabled,...
how can convert selectitem in combobox from string to form??

Re: Convert String DataType To Form Object

Christian Graus7-Jul-09 3:20