I have given each checkbox item on my application a value. I have group of checkboxes and I need to add up their total value base on user selection. I am using this code but it's not working for sum. I do not want to use if a.checked then add this elseif this checked add that kind of way.
Dim abe As CheckBox = groupAlumni.Controls.OfType(Of CheckBox)().Where(Function(r) r.Checked = True).Sum()
MsgBox(abe.Tag)
.sum part is giving an error. How can I achieve this?
Option 2
Also I am thinking I could change checkbox names to cb0 to cb15 and create a while loop and check them one by one to see which ones are selected and add up their values. How can I change cb number during while loop?
I wrote this but I really need cb0 to be cb1,cb2 and continue until cb15 during the loop.
If anybody answers either option it's fine for me. Thank you!
Dim counter As Integer = 0
Dim cbScore As Integer = 0
While counter < 15
If cb0.Checked Then
cbScore += cb0.Tag
End If
counter += 1
End While
If you only need the sum of the values, try this:
cbScore = groupAlumni.Controls.OfType(Of CheckBox)().Where(Function(r) r.Checked).Sum(Function(r) CInt(r.Tag))
Removed due to not compiling and incompatible methods.
Related
I am trying to add columns dynamically to data grid view using VB.net. But the issue is I need to check that the column name already exists. before adding it if exists I want it to be cancelled automatically. I am using another form to select the Job Nos. which will add as Datagridview Header Text when it saved. () below is the code I am using to add a column to my datagridview. Hope you understand the question. I found some nearby answers in C# unfortunately I am not able to convert those correctly as my C# coding knowledge is little weak.
Thank You!
Dim FRMP = FrmEReview.ReviewGrid.Columns
Dim NOHRS As New DataGridViewTextBoxColumn
FRMP.Add(NOHRS)
NOHRS.HeaderText = Me.Cmb_CName.Text & "-" & Me.Cmb_DName.Text
NOHRS.Width = 160
The obvious option - the one you should have been able to work out for yourself - is to simply loop through the columns and test the HeaderText of each one:
Dim headerText = $"{Cmb_CName.Text}-{Cmb_DName.Text}"
Dim headerTextFound = False
For Each column As DataGridViewColumn In FrmEReview.ReviewGrid.Columns
If column.HeaderText = headerText Then
headerTextFould = True
Exit For
End If
Next
If Not headerTextFound Then
'...
End If
This is basically the code equivalent of what you'd do manually, which is why you should have been able to do it for yourself, at least mostly.
The not-so-obvious solution for a beginner is to use LINQ. LINQ is basically a means to flatten loops like this, so it leads to far more succinct code:
Dim headerText = $"{Cmb_CName.Text}-{Cmb_DName.Text}"
If FrmEReview.ReviewGrid.
Columns.
Cast(Of DataGridViewColumn)().
All(Function(dgvc) dgvc.HeaderText <> headerText) Then
'...
End If
for an assignment in my class I had to make a super simple point of sale system and one of the features required was tracking how many of each item is sold. I know I can do it with If statements such as
If DropDownList.SelectedIndex = 0 Then
ddl1Tracker += 1
ElseIf DropDownList.SelectedIndex = 1 Then
ddl2Tracker +=1
Etc...
End IF
but I was wondering if there was a better way to do it so I don't need to make a variable to track each individual item?
Thanks
You could replace a bunch of ddlNTracker variables with an array:
Dim ddlTrackers(ddlCount-1) as Integer
And then replace the whole If section with a single function call:
ddlTrackers(DropDownList.SelectedIndex) += 1
So i want to perform some code N times. N is textbox's value (e.g: 12).
I have no idea how to accomplish this, but something like this is on my mind:
For Each i as 1 in textbox1.text
'some code
Next
or
dim num1 as integer = 0
While num1 < textbox1.text
'some code
num1 += 1
Next
Those were just some ideas that were on my mind when i though about this question, none of above is tested nor tried to code.
Any ideas?
First and foremost, turn on Option Strict. This will save you time in the long run by converting possible runtime errors into compiler errors. At the top of the code file:
Option Strict On
It can also be set for the entire project:
Project Properties -> Compile Tab -> Option Strict selector: On
You can also make it the default for all new projects via:
Tools -> Options -> Projects and Solutions -> VB Defaults
What it Does
TextBox.Text always contains text (hence the clever names). "12" is just a string and is not the same as 12. So, before you can use it, you need to convert from string to integer. Note: If you want to restrict user input to numbers consider using a NumericUpDown.
There are several ways to convert, but considering that the data comes from a user, we have to allow that they may enter "I like pie" instead of numerals. So, we want to use the safest method which in this case is Integer.TryParse:
' declare int var to hold the result
Dim LoopCount As Integer
If Integer.TryParse(TextBox132.Text, LoopCount) Then
' success! LoopCOunt contains the integer value of the Text control
For n As Integer = 0 To LoopCount - 1
' some code to do something
Next
Else
' failed - scold the user with a MessageBox
End if
The comments in the code explain, but first you declare an integer variable to hold the converted value. Integer.TryParse is a function which will return True/False. If it succeeds, your variable will hold the integer value.
See Converting DataTypes for Option Strict for other convert methods and cases where they are appropriate.
This might work, I haven't tried:
Dim repeat_times as Integer = 0
Do Until repeat_times = 10 'times you want to repeat
repeat_times = repeat_times + 1
Console.WriteLine("Hello World") 'or anything you want
Loop
For n As Int32 = 0 To TextBox1.text - 1 was an answer for my question.
It would take too long to try an explain the actual application I am building.
Lets just say, I have 3 textboxes on my form. I want to set each one of them to a value of the numerical index. This is how I would normally do it.
txt1.Text = "1"
txt2.Text = "2"
txt3.Text = "3"
Now, if I had 100 of these textboxes, I would want to do something more like this.
For i as Integer = 1 to 3
txt[i].Text = i
Next
Is this possible?
This is how I would do it: first, create a list or an array (depending on whether the number of textboxes is fixed or not) and add you textboxes to it:
Dim txtList as new list(of textbox)
txtList.items.add(txtBox1...
This can be done automatically using jmcilhinney's method (with the same caveats):
Dim txtList = New List(Of TextBox)(Me.Controls.OfType(Of TextBox)().ToArray())
Then you can reference it as such:
txtList(i).text
I hope that's what you were asking and that it helps :)
Is it possible to convert, say, a textbox input to working code?
For example, user types 'if x<10 then y=2 else y=5' into textbox1, it gets used directly as code something like ...
dim x as integer = 5
dim y as integer = 0
include processed textbox1.text
resultbox.text = (y*20).tostring
It's not important why this would be needed - just whether there is any straight-forward method that parses a string to code.
Many thanks.
Maybe this is what you are looking for:
http://www.codeproject.com/Articles/12852/Compile-and-Run-VB-NET-Code-using-the-CodeDom
yes you can do this using the VBCodeProvider class. Although the amount of code required is quite significant:
http://www.codeproject.com/Articles/5472/Compiling-NET-code-on-the-fly