Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people, just like you, are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
Solved

Why is optional char argument nothing, not empty string?

Posted on 2010-09-15
2
365 Views
Last Modified: 2013-11-07
I have the following vb.net routine in an asp.net page:
   Private Sub GetGridData( _
         Optional ByVal sStatus As String = "New", _
         Optional ByVal sBookmark As Char = "")

      Dim sSQL As String
      Dim sWHERE As String = "WHERE 1=1 "

      If sStatus <> "Enabled" Then
         sBookmark = ""
         dlBookmark.Visible = False
      Else
         ' Do something else
         sBookMark = "x"
      End If

      sSQL = "SELECT * FROM MySQLView " & sWHERE

      If sBookmark <> "" Then
         ' FixSQL wraps single quotes around a string
         sSQL &= "AND Left(Name, 1) = " & FixSQL(sBookmark) & " "
      End If

      sSQL &= "ORDER BY Status, Name"

      Dim dr As SqlDataReader = dbHelper.OpenDataReader(sSQL)

      MyDataGrid.DataSource = dr
      MyDataGrid.DataBind()
   End Sub

Open in new window


This code no longer works when called as follows:
   GetGridData()

Open in new window


sBookmark has a value of nothing in the routine, not "", even after being assigned to string.empty. I know this used to work and I'm wondering if a change earlier this year from 1.1 to 2.0 / 3.0 / 3.5 treats chars differently. I can fix the code using a string instead of a char but I'm not sure why the car isn't set to an empty string either by the optional argument value or by the explicit assignment when status <> "Enabled".

Thanks in advance.
0
Comment
Question by:ZekeLA
2 Comments
 
LVL 75

Accepted Solution

by:
käµfm³d   👽 earned 250 total points
ID: 33686748
There does not exist a character which equates to "empty". Strings can be empty, but characters cannot. The closes you can get is the null character, which is what I believe VB is assigning to your sBookmark.
0
 
LVL 1

Author Comment

by:ZekeLA
ID: 33686910
OK. What's strange is I checked my source control repository and this code hasn't changed in 4 years. But I know it used to work. Thanks.
0

Featured Post

Master Your Team's Linux and Cloud Stack!

The average business loses $13.5M per year to ineffective training (per 1,000 employees). Keep ahead of the competition and combine in-person quality with online cost and flexibility by training with Linux Academy.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A quick way to get a menu to work on our website, is using the Menu control and assign it to a web.sitemap using SiteMapDataSource. Example of web.sitemap file: (CODE) Sample code to add to the page menu: (CODE) Running the application, we wi…
Problem Hi all,    While many today have fast Internet connection, there are many still who do not, or are connecting through devices with a slower connect, so light web pages and fast load times are still popular.    If your ASP.NET page …
Finds all prime numbers in a range requested and places them in a public primes() array. I've demostrated a template size of 30 (2 * 3 * 5) but larger templates can be built such 210  (2 * 3 * 5 * 7) or 2310  (2 * 3 * 5 * 7 * 11). The larger templa…
In a recent question (https://www.experts-exchange.com/questions/29004105/Run-AutoHotkey-script-directly-from-Notepad.html) here at Experts Exchange, a member asked how to run an AutoHotkey script (.AHK) directly from Notepad++ (aka NPP). This video…

856 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question