Ad:

VB.NET Discussion Thread
Unsolved
Views: 4313

Aug 13th, 2008

Variable declaration!!!

Expand Post »

I have a class named Account so I have a question. In the declarations of a new instance

Dim Newaccount as Account -----but I can declare this like..
Dim Newaccount As Account = New Account

which are the differences between both declarations?? are the same or not?

excuse me english...

besides I have another question

I have 3 functions in mi clasee

writename()
writeaccount()
writesave()

the first 2 functinos are string..so i have this.

IF name = "" then
Console.writeline("name is empty")

is the same with account and save
but the problem with save is DOUBLE so if is ="" ..I have this error.....saying....Conversion string "" in TYPE DOUBLE is invalid.............

what I can do??? because I want textmessage saying "save is empty" IF is empty

Last edited by gouki2005; Aug 13th, 2008 at 4:37 am.

Similar Threads

const reference variable declaration more efficient ? in C++
Help with variable declared inside an if block in C++
Regardind variable declaration in C++
Structure Help Please in C++
10, 20, 0 in C

gouki2005

Reputation Points: 10

Solved Threads: 0

Light Poster

Offline

36 posts
since Jun 2008

Permalink

Aug 13th, 2008

Re: Variable declaration!!!

The first just declares a variable as the class. The second creates an instance of it.
Without seeing your code I would say you need to put in "Exit Sub" after your If statement.
If it is a subroutine:

VB.NET Syntax (Toggle Plain Text)
IF name = "" then Console.writeline("name is empty") : Exit Sub
IF name = "" then Console.writeline("name is empty") : Exit Sub

If it is a function:

VB.NET Syntax (Toggle Plain Text)
IF name = "" then Console.writeline("name is empty") : Return Nothing
IF name = "" then Console.writeline("name is empty") : Return Nothing

Last edited by waynespangler; Aug 13th, 2008 at 5:50 am.

waynespangler

Reputation Points: 84

Solved Threads: 58

Posting Pro in Training

Offline

461 posts
since Dec 2002

Permalink

Aug 13th, 2008

Re: Variable declaration!!!

Sorry..the 3 are not function the 3 are SUb.....so how can I fix the error with double type..string is not a problem....but when is double...a exception..appears..

beside the diffrences between

use a instance of the class with using a variable.to use the class...like my first post

Last edited by gouki2005; Aug 13th, 2008 at 1:42 pm.

gouki2005

Reputation Points: 10

Solved Threads: 0

Light Poster

Offline

36 posts
since Jun 2008

Permalink

Aug 13th, 2008

Re: Variable declaration!!!

hi,

Quote ...

Dim Newaccount as Account -----but I can declare this like..
Dim Newaccount As Account = New Account

First one is just a Reference not Referring any object. With out referring any object using reference (Like first one) is an exception (NullPointerException)

Second one is a reference and referring an Account object.

And then

Are you mean how to check when double valued field is left out? I think so

when no value given to double (that is default value ) is 0.0

So

VB.NET Syntax (Toggle Plain Text)
Dim Save As Double
.....
  If Save = 0.0 Then
        MessageBox.Show ("Empty Double")
  End If
Dim Save As Double
.....
  If Save = 0.0 Then
        MessageBox.Show ("Empty Double")
  End If

selvaganapathy

Reputation Points: 44

Solved Threads: 101

Posting Pro

Offline

547 posts
since Feb 2008

Permalink

Aug 13th, 2008

Re: Variable declaration!!!

Click to Expand / Collapse Quote originally posted by selvaganapathy ...

hi,

First one is just a Reference not Referring any object. With out referring any object using reference (Like first one) is an exception (NullPointerException)

Second one is a reference and referring an Account object.

And then

Are you mean how to check when double valued field is left out? I think so

when no value given to double (that is default value ) is 0.0

So
VB.NET Syntax (Toggle Plain Text)
Dim Save As Double
.....
  If Save = 0.0 Then
        MessageBox.Show ("Empty Double")
  End If
Dim Save As Double ..... If Save = 0.0 Then MessageBox.Show ("Empty Double") End If

yeah but I am creating the error message in the sub..beside..is not working.neither...if the user doesnt write nothing and the field is empty like this = "" a exception appears I try the 0.0 but nothing the same.. string "" cant convert to double

Public Sub save(ByVal sav As Double)
If sav= 0.0 Then
Console.WriteLine("Is not valid")

Else

mainsave = sav
End If

gouki2005

Reputation Points: 10

Solved Threads: 0

Light Poster

Offline

36 posts
since Jun 2008

Permalink

Aug 14th, 2008

VB.NET Project

i need sample project using vb.net if u know anything please send me

uma123

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

2 posts
since Aug 2008

Permalink

Aug 14th, 2008

Re: Variable declaration!!!

i need vb.net sample projects

uma123

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

2 posts
since Aug 2008

Permalink

Aug 14th, 2008

Re: Variable declaration!!!

Quote ...

VB.NET Syntax (Toggle Plain Text)
Public Sub save(ByVal sav As Double)
If sav= 0.0 Then
Console.WriteLine("Is not valid")
 
Else
 
mainsave = sav
End If
Public Sub save(ByVal sav As Double) If sav= 0.0 Then Console.WriteLine("Is not valid") Else mainsave = sav End If

what I understand that the user will enter the value in textbox , after you check that user did not leave it empty you can use it .

VB.NET Syntax (Toggle Plain Text)
 
        Dim save As Double
        If TextBox1.Text = "" Then  ' check if the textbox is empty
            save = 0.0
            MessageBox.Show("Empty Double")
        Else
            save = Convert.ToDouble(TextBox1.Text) 'if it is not empty convert the string to double and store it in save variable 
 
        End If
        Dim save As Double
        If TextBox1.Text = "" Then  ' check if the textbox is empty
            save = 0.0
            MessageBox.Show("Empty Double")
        Else
            save = Convert.ToDouble(TextBox1.Text) 'if it is not empty convert the string to double and store it in save variable 
            
        End If

also you can validate the user's input before you store it in save variable.
I hope that help you

Quote ...

i need sample project using vb.net if u know anything please send me

it is better you open new thread, and i suggest to search here since many ask same thing , Good Luck

Last edited by manal; Aug 14th, 2008 at 11:24 am.

manal

Reputation Points: 37

Solved Threads: 17

Junior Poster

Offline

122 posts
since Mar 2006

This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

Previous Thread in VB.NET Forum Timeline: Project idea ! !

Next Thread in VB.NET Forum Timeline: VB.Net for AutoCAD

DaniWeb Message

Cancel Changes

User Name
Password