Most Concise Way To Handle / Is Nothing / Empty String Check?
Apr 1, 2011
What is the best way to checkt o see if the TelephoneNumber property has some string in it that does not Trim down to an empty string? I hate to use the Trim VB.NET function on Nothing just to give me an empty string whenever the TelephoneNumber is Nothing. [code] What puzzles me is that the "IsNullOrEmpty" function works as an extension method of a string instance even if the String is NOTHING. Why does this extension method work but the follow straight - .NET code raise an exception? [code]
Let's say I have the following string:"/encryption:aes128 /password:<PASSWORDHERE> /log:log.txt"
I need to write this to a log file but the password needs to be masked (replaced with asterisks for example).I can do this easily with String.IndexOf and String.Replace in a few lines of code but I'm interested in seeing how others would implement this so that the code is as short and concise as possible. A one line replace function would be best.
My goal here is to see/learn some new techniques of combining string functions.
I'm using FileHelper to generate object's property. Here is an example of one property:
<FieldOptional(), _ FieldTrim(TrimMode.Both)> _ <FieldNullValue(GetType(String), " ")> _ Public StoreNo As String
As you can see the StoreNo will either have a value or " ", one of the business policy is to check if the StoreNo is empty or nothing if the object's StoreNo is empty or null then the record will not create.
I though about creating an HasValue Function in the class to check the StoreNo and other properties in the object but I feel like it is a hack.
Public Function HasValue() As Boolean Dim _HasValue As Boolean = True If StringHelper.IsNullOrBlank(Me.StoreNo) Then
[Code]....
I don't think this approach is an ideal solution. what if the StoreNo is remove or change to something else. What's the best approach to check object's property?
This must've have been asked before but I couldn't locate it. In a mixed code project (VB and C#) we were debugging some old Visual Basic code where a statement as follows could be found:
If Request.Params("xxx") <> "" Then 'do something
I considered this a bug as Request.Params could be null, in which case the statement would've become false which wasn't the idea. So I thought. I just found out, -- probably for the tenth time and I will keep forgetting -- that the following two statements are not equal, while Nothing in VB should be equal to null in C# (thought I):
if(String.Empty == null) // always false If String.Empty = Nothing Then ' always true
Should I dismiss this as a typical Microsoft backward compatibility effort, or should I consider this a huge error in the VB.NET compiler? Does anybody know the Microsoftean opinion on this oddity?
In my attempts to understand vb.NET, one of the problems I have encountered is that I have not been able to find a concise definition anywhere for the Paint Event. So after many hours of researching and forum posts (and my own personal tests), here is my own definition (but it seems to fail in one instance, mentioned after the definition). I would like to create a final definition based on everyone's input, but keep in mind, the idea here is to STAY CONCISE. So here goes:
Explanation of the Paint Event
Whenever any portion of a control is UNCOVERED (except by the mouse pointer), the paint event fires. Covering of the control does not fire the event, because the covered area is not visible to the user, and is therefore irrelevant. The paint event is a messenger that alerts the program, via message, that some portion of the control has been uncovered and this message launches an OPTIONAL paint event handler (paint event procedure) written by the programmer, if one is needed to handle those situations when the event occurs. One possible situation is the most obvious...the need to redraw the uncovered region. A paint event procedure is the programmer's counterpart to vb6's automatic property, "AutoRedraw". But whereas vb6's solution was a simple and automatic redraw of the control, vb.NET's equivalent requires the programmer to define explicitly how the event is to be handled, whether it be a simple redraw or something more elaborate. This puts this event in a special category; it is not a user-desired event fired by some user-desired action...it is an internally generated event that acts more as a housekeeping "watchdog" to alert the program that housekeeping chores may have to be implemented because the user did something that was NOT DIRECTLY RELATED to a desired action. For example, when the user moves a window over a control in such a manner that a portion of the control is covered, then uncovered, this causes the state of the control to change even though the user did not specifically request it. It nonetheless may have to be dealt with, and this is managed via the paint event handler procedure.
The problem I have with this definition of mine, is that if the above is true, then why does the mouse moving across the control NOT cause the paint event to fire? After all, it is causing areas of the control to be covered and then uncovered. Is it because the mouse is a special case where the system puts the mouse pointer on a separate layer above the screen graphics, in order to prevent constant paint event messaging?
i have a dataset that takes results from a select to a sql database. the select returns rows and sometimes returns no rows. how can i check if the dataset has no rows from the select? [Code]
I need to check if a .txt file is empty, if it's not, the code will read the file and process the information.I know how to read .txt file. Is there a way to check if the .txt file is empty? not an empty line just completely empty?
On a button click I need to test whether or not an array has been filled, if it has the user gets linked to a new form otherwise they receive a message box telling them to first assign values to the array.
I've tried 'If MyArray Is Nothing Then....' and 'If MyArray.Length < 1 Then...' but neither seemed to have worked.
I was wondering how to check if a list box is not empty I have inserted my code I want t check if there if text in the listbox and if there is no text do some thing. I have put the line of code i am having trouble with in red
result = MsgBox("Are you sure you wish to make the required number of lockers", MsgBoxStyle.YesNo, "Confirm Order") If (result = MsgBoxResult.Yes) Then CheckLevels() If lstOrder.NoItems = True Then
I've done an internet search to determine if I can detail if a SQLDataAdapter is empty after running an SQLCommand? My research so far point I can't check if the SQL dataAdapter is empty until I bind it to a dataset/datatable. Ideally would not like to run another SQL command to do a row count to determine if query retruns rows or not. I'm populating a datagridview and would like to alert the user that there is no data to view. What's the most efficent way to check if an SQLDataAdapter is empty?
i want to insert the data into the table only if the table is empty, so for that i need to check the condition to check whether data already exists in the table, if present then i want to empty the table before inserting the the fresh value. i know how to insert and delete the data only prob is to check the condition. so please can any help me out in this.
TO INSERT
Dim comUserSelect As OleDbCommand myDateTime(i) = DateTime.Parse(arr_dateTime(i)) ' Console.WriteLine(r("P1"))
How to test the stacks if it is already empty? I tried Stacks.IsEmpty but unfortunately I have an error says: IsEmpty is not declared.. Is there any way to test if the stack is empty? When I'm typing (after dot) there is no IsEmpty properties of the stack.
Possible Duplicate: Checking for an SQL result in VB.NET I have login form which is redirect user for their levels but before to that if there is no any user on the data table I would like to redirect to create admin form. I have all the forms but I didn't manage to redirect them because I don't know how to create statement.
Dim con As SqlCeConnection Dim command As SqlCeCommand con = New SqlCeConnection("Persist Security Info=False;Data Source=.database.sdf;Password=********;File Mode=shared read") con.Open() [Code] .....
I have this code is working. What to write for Private Sub frmlogin_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load End Sub
Here is my problem-> I have three folders that I need to check if they are empty or not, if one of them is empty, I would like to keep checking the other two, if they are not empty I want to do something and then check the other two, but not all the time all three will be empty or not empty there might be times where one folder has something and the other two not and so on. I just want to check a folder and if its empty go to the next one but if not do something and still g to the next one to check if it empty or not, an so on.
Ive got a Form application in VB.NET.I have many text boxes on one form (about 20). Is there anyway to check them all at once to see if they are empty instead of writing out a massive line of code to check each one individually such as
If txt1.text = "" Or txt2.text="" Then msgbox("Please fill in all boxes")
I have a code in Save Button, and part of it, a code that checks if the dynamic text boxes that has been created is empty. But when the system runs, it only check the first set of text box and an an message appears "Collection was Modified; enumareation operation may not execute.".
Here's the code:
Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click Try For Each txt As TextBox In TextBoxes2 If String.IsNullOrEmpty(txt.Text) Then
I'm trying to retrieve some data from an Excel with the following [code]...
At some point the Recordset encounters an empty cell which it can't assign as a to Recordset.Fields("BG").Value. VB2010 will then throw an error: When casting from a number, the value must be a number less than infinity.
First time poster and new to ASP programming.I have a functional database to where i am trying to add new functionality.I'm trying to add the idea to check if a returned string is empty, if so get value from a backup table which holds historical information. Here is what i have got for the specific part:
I have numerous textboxes which I use to gather data to be placed into an array. But I want to ensure, before I place them to the array,that there is at least one character (letter or number, no space) in each textbox. Seeing as I have about two dozen, it would seem tedious to write an If...Then statement for each of them. And I cannot use a custom textbox class for this. So how can this be done?
im getting a image from my database to a data set. before i convert it to a proper picture i need to check whether ds.Tables("userDetails").Rows(0).Item("photo") is EMPTY or NOT. How should i write the if condition? <code>If ds.Tables("userDetails").Rows(0).Item("photo")<> ??? Then
Dim pictureData As Byte() = DirectCast(ds.Tables("userDetails").Rows(0).Item("photo"), Byte()) Dim picture As Image = Nothing Using stream As New IO.MemoryStream(pictureData) picture = Image.FromStream(stream) End Using
I am using VB.net to create a simple winform. I have the option to save the data I input on that form. I am trying to prevent the user not to save the data if textbox10 is empty. I tried the while loop but I go into an infinite loop. The code is below. The if statement gives the error but allows the user to save.
