Concatenation of variable name being passed in .Net VB

Question

I have over 20 text boxes set up and what I'm trying to do is take the value out of each one of them and place it an array of values (structure). Each of my text boxes has a name of txtScore00, 01, 02 and so on and I'm trying to loop them with a counter and use the counter as numbers in my variable name. I found this topic Concatenate Variable Names in VB but i still cant get it to work. Any suggestions? My code populating the array:

For intCountOne = 0 To aStudent.Length - 1
        For intCountTwo = 0 To aStudent(intCountOne).decGrade.Length - 1
            aStudent(intCountOne).decGrade(intCountTwo) = Me.Controls("tbScore" & intCountOne & intCountTwo).Text

Tried adding 4 spaces to make it look like a code and didnt work, didnt want to make the question to look like trash — LittleB0Y, Nov 20 '14 at 21:58
@LittleB0Y, leave the code, other people will edit it to make it look good. — Nathan Koop, Nov 20 '14 at 21:58
When i fill the boxes it say that the object reference is not set to an object. — LittleB0Y, Nov 20 '14 at 22:00
possible duplicate of [What is a NullReferenceException and how do I fix it?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it), YOur array is probably not initialized — Ňɏssa Pøngjǣrdenlarp, Nov 20 '14 at 22:12
I tried a sample easy code: aStudent(1).decGrade(1) = "Hello" MessageBox.Show(aStudent(1).decGrade(1)) And throws out the same error. — LittleB0Y, Nov 20 '14 at 22:29

score 1 · Answer 1 · answered Nov 20 '14 at 23:05

You have:

Me.Controls("tbScore" & intCountOne & intCountTwo)

Which requires the TextBoxes to be directly contained by the Form. If they are in a different container, like a Panel, then you'd need to change "Me" to the name of the container (such as "Panel1").

Alternatively, you can search the Form for a control with that name, which is quite useful if the TextBoxes are spread out over multiple containers (it'll still work if they are all in the same container).

Here's a quick example:

    Dim matches() As Control
    For intCountOne = 0 To aStudent.Length - 1
        For intCountTwo = 0 To aStudent(intCountOne).decGrade.Length - 1
            matches = Me.Controls.Find("tbScore" & intCountOne & intCountTwo, True)
            If matches.Length > 0 AndAlso TypeOf matches(0) Is TextBox Then
                Dim tb As TextBox = DirectCast(matches(0), TextBox)
                aStudent(intCountOne).decGrade(intCountTwo) = tb.Text
            End If
        Next
    Next

figured it out, the issue was that i was looping all of it within a group box, got rid of it and works perfecly — LittleB0Y, Nov 20 '14 at 23:08
Yes...probably because of the reason I stated. I'm guessing you moved the controls from the GroupBox to the Form? If you use code like I posted above then it doesn't matter which container they are in as they will always be found. — Idle_Mind, Nov 20 '14 at 23:13

Concatenation of variable name being passed in .Net VB

1 Answers1